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Write down the general molecular formula for the alkene series. Using this formula, calculate the number of hydrogen atoms present in a decene molecule, which possesses exactly 10 carbon atoms. | **Final Answer:** 20 hydrogen atoms General formula: $C_{n}H_{2n}$ For decene: $n = 10$ $$H = 2 \times 10 = 20$$ | Chemistry 10th JEE |
Identify the common organic compound (a carboxylic acid) that is the primary constituent of vinegar and provide its IUPAC name along with its chemical formula. | **Final Answer:** Ethanoic acid ($CH_{3}COOH$) $\text{Primary constituent of vinegar} = \text{Acetic acid}$ $\text{Chemical formula} = CH_{3}COOH$ $\text{IUPAC name} = \text{Ethanoic acid}$ | Chemistry 10th JEE |
Identify the specific chemical reaction process used in the food industry to convert liquid vegetable oils (unsaturated fats) into solid fats (saturated fats) like margarine. Mention the type of catalyst typically required for this transformation to occur. | **Final Answer:** The process is Catalytic Hydrogenation and the catalyst is Nickel (Ni). $$ \text{Vegetable Oil (Unsaturated)} + H_{2(g)} \xrightarrow{Ni, \text{Heat}} \text{Vegetable Ghee (Saturated)} $$ $\text{Reaction Process} = \text{Catalytic Hydrogenation}$ $\text{Catalyst Required} = \text{Nickel (Ni)}$ | Chemistry 10th JEE |
An alkyl group is formed by the removal of one hydrogen atom from an alkane molecule. Consider the three structural representations of alkyl groups provided in the accompanying figure:
(a) Identify which of the labeled structures (i, ii, or iii) represents the **n-butyl** group.
(b) Provide the appropriate common name... | **Final Answer:** (a) Structure (i) is n-butyl; (b) (ii) is isobutyl, (iii) is sec-butyl; (c) $2^{\circ}$ carbon atom. (i) $CH_{3}-CH_{2}-CH_{2}-CH_{2}-\rightarrow \text{Straight chain butyl} \rightarrow \text{n-butyl}$ (ii) $(CH_{3})_{2}CH-CH_{2}-\rightarrow \text{Methyl at second last carbon} \rightarrow \text{isobut... | Chemistry 10th JEE |
Define the term used in organic chemistry to describe molecules that possess the identical molecular formula but exhibit different structural arrangements, resulting in distinct physical and chemical characteristics. | **Final Answer:** Isomerism $\text{Molecular Formula}_{A} = \text{Molecular Formula}_{B}$ $\text{Structural Arrangement}_{A} \neq \text{Structural Arrangement}_{B}$ $\text{Term} = \text{Isomerism}$ | Chemistry 10th JEE |
Analyze the structure of neopentane, represented as $(CH_3)_4C$. Determine the number of primary, secondary, and tertiary hydrogen atoms present in this molecule. Based on your analysis, explain why it lacks any tertiary hydrogen atoms. | **Final Answer:** Primary H = 12, Secondary H = 0, Tertiary H = 0 Structure of neopentane: $(CH_{3})_{4}C$ $n(1^{\circ} C) = 4$ and $n(4^{\circ} C) = 1$ $1^{\circ} H = 4 \times 3 = 12$ $2^{\circ} H = 0, 3^{\circ} H = 0$ (since $n(2^{\circ} C) = 0$ and $n(3^{\circ} C) = 0$) | Chemistry 10th JEE |
Provide the systematic IUPAC name for the compound whose common name is ethyl cyanide ($CH_3CH_2CN$). Show how the total number of carbon atoms determines the root word of the nitrile. | **Final Answer:** Propanenitrile Total carbons ($n$) = $\text{carbons in ethyl group} + \text{carbon in cyano group}$ $n = 2 + 1 = 3$ Root word for $n=3$ = $\text{propane}$ IUPAC Name = $\text{propane} + \text{nitrile} = \text{propanenitrile}$ | Chemistry 10th JEE |
Primary alcohols can undergo step-wise oxidation. Predict the two possible organic compounds formed during the controlled and then complete oxidation of propan-1-ol ($CH_3CH_2CH_2OH$), and name the functional groups present in these products. | **Final Answer:** Controlled oxidation product: Propanal (Aldehyde, $-CHO$); Complete oxidation product: Propanoic acid (Carboxylic acid, $-COOH$) $$CH_{3}CH_{2}CH_{2}OH \xrightarrow{PCC} CH_{3}CH_{2}CHO$$ $$CH_{3}CH_{2}CHO \xrightarrow{KMnO_{4}/H^{+}} CH_{3}CH_{2}COOH$$ | Chemistry 10th JEE |
Predict the product formed when propyne ($CH_3-C\equiv CH$) reacts with excess hydrogen gas ($H_2$) in the presence of a nickel ($Ni$) catalyst. Write the balanced chemical equation and provide the IUPAC name of the saturated hydrocarbon produced. | **Final Answer:** Propane ($CH_3-CH_2-CH_3$) Using general alkyne hydrogenation: $C_{n}H_{2n-2} + 2H_{2} \xrightarrow{Ni} C_{n}H_{2n+2}$ $CH_{3}-C\equiv CH + 2H_{2} \xrightarrow{Ni} CH_{3}CH_{2}CH_{3}$ $IUPAC Name: \text{Propane}$ | Chemistry 10th JEE |
In IUPAC nomenclature, when multiple identical substituents are branched off the main carbon chain, specific prefixes are added to the name of the substituent. State the prefixes used for two, three, and four identical groups respectively. | **Final Answer:** di-, tri-, tetra- $n = 2 \implies \text{di-}$ $n = 3 \implies \text{tri-}$ $n = 4 \implies \text{tetra-}$ | Chemistry 10th JEE |
Evaluate the structure of benzaldehyde ($C_6H_5CHO$). Determine its systematic IUPAC name and explain whether it belongs to the aliphatic or aromatic class of aldehydes based on the nature of the carbon group attached to the functional group. | **Final Answer:** IUPAC Name: Benzenecarbaldehyde; Class: Aromatic Aldehyde Given structure: Benzaldehyde ($C_{6}H_{5}CHO$). Analysis: The formyl group ($-CHO$) is directly bonded to the phenyl ring ($C_{6}H_{5}$). Systematic IUPAC name: For $-CHO$ attached to a benzene ring, the name is: $$\text{Benzenecarbaldehyde}$$... | Chemistry 10th JEE |
Determine the systematic IUPAC name for the organic compound shown in the structural formula below. Explain your reasoning for the numbering of the parent carbon chain based on the lowest locant rule. | **Final Answer:** 2-chlorobutane $\text{Longest carbon chain} = 4 \text{ atoms} \rightarrow \text{butane}$ $\text{Substituent} = -Cl \rightarrow \text{chloro}$ $\text{Locant comparison: } L \rightarrow R = 2; R \rightarrow L = 3$ $\text{Lowest locant rule: } 2 < 3 \rightarrow \text{locant is } 2$ $\text{IUPAC Name} = \... | Chemistry 10th JEE |
Match the classes of organic compounds listed in **Column-I** with their corresponding functional group structures provided in **Column-II**:
**Column-I (Class of compound)**
a) Ketones
b) Haloalkanes
c) Nitroalkanes
d) Ethers
**Column-II (Functional group Structure)**
p) $>C=O$
q) $-X$ (where $X = F, C... | **Final Answer:** (a)-(p), (b)-(q), (c)-(r), (d)-(s) Ketones $\rightarrow$ $ >C=O $ group $\rightarrow$ Match (a)-(p) Haloalkanes $\rightarrow$ $ -X $ group $\rightarrow$ Match (b)-(q) Nitroalkanes $\rightarrow$ $ -NO_{2} $ group $\rightarrow$ Match (c)-(r) Ethers $\rightarrow$ $ -O- $ group $\rightarrow$ Match (d)-(s) | Chemistry 10th JEE |
Evaluate the validity of the following statements regarding organic compounds and common chemical substances:
**Statement (A):** Propanal is a carbon-based compound that contains the functional group $-CHO$.
**Statement (B):** Dry ice, used as a cooling agent, consists of solid $CO_2$.
**Statement (C):** The IUPAC sys... | **Final Answer:** Statements (A), (B), and (C) are all correct. $\text{Propanal} \rightarrow CH_{3}CH_{2}CHO \implies \text{Functional Group} = -CHO$ $\text{Dry Ice} \rightarrow CO_{2} (s) \implies \text{Solid Carbon Dioxide}$ $R-COOH \implies \text{IUPAC Suffix} = -oic\ acid$ | Chemistry 10th JEE |
Determine the IUPAC name for the branched hydrocarbon shown in the figure below. In your solution, clearly explain the steps taken to identify the principal carbon chain and the specific IUPAC rules used to determine the numbering direction for the substituents. | **Final Answer:** 2-chloro-3-methylbutane Principal chain: Longest continuous carbon sequence $= 4$ carbons $\rightarrow$ Butane Locant sets: From left $(2, 3)$, from right $(2, 3)$ Alphabetical priority: Chloro ($C$) $<$ Methyl ($M$) $\rightarrow$ Numbering starts from right Combined name: $2-chloro$ $+$ $3-methyl$ $+... | Chemistry 10th JEE |
Provide the systematic IUPAC name for the saturated hydrocarbon isomer commonly referred to by the trivial name neo-pentane, which is characterized by having a single quaternary carbon atom. | **Final Answer:** 2,2-dimethylpropane Molecular Formula Identification: $C_{n}H_{2n+2} \rightarrow C_{5}H_{12}$ Quaternary structure: $C(CH_{3})_{4}$ Parent chain determination (longest chain): $3 \text{ carbons} \rightarrow \text{propane}$ Locant and substituent identification: $2,2\text{-dimethyl}$ | Chemistry 10th JEE |
In the IUPAC priority series for naming polyfunctional organic compounds, certain functional groups take precedence over others to determine the principal functional group. Among the following four groups, identify the one that holds the highest priority:
1. $-OH$ (hydroxyl group)
2. $-CN$ (nitrile group)
3. $-CO-$ (ca... | **Final Answer:** Option (4): $-CONH_{2}$ Given groups: $-OH$ (hydroxyl), $-CN$ (nitrile), $-CO-$ (ketone), and $-CONH_{2}$ (amide). Applying IUPAC priority hierarchy: $\text{Amides} > \text{Nitriles} > \text{Ketones} > \text{Alcohols}$ $$-CONH_{2} > -CN > -CO- > -OH$$ | Chemistry 10th JEE |
The chemical structure of compound (M), which is the primary constituent of the oil of wintergreen and is widely used as a flavoring agent and a topical analgesic, is provided below.
1. Identify the two specific functional groups present in molecule (M).
2. According to the IUPAC rules for priority of functional grou... | **Final Answer:** Methyl 2-hydroxybenzoate Functional groups: $-COOCH_{3}$ (methyl ester) and $-OH$ (phenol/hydroxyl) $\text{Priority: Ester} > \text{Alcohol} \Rightarrow \text{Suffix: -oate (principal group), Prefix: hydroxy (substituent)}$ Ring numbering: $C_{1}$ at $-COOCH_{3}$ attachment; $C_{2}$ at $-OH$ attachmen... | Chemistry 10th JEE |
Methyl salicylate is an organic ester commonly known as oil of wintergreen, frequently used as a flavoring agent and in topical ointments for pain relief due to its analgesic properties. Its molecular structure is shown below as compound (B). Carefully examine the bonding in this structure and calculate the total numbe... | **Final Answer:** 19 Given: Molecular formula is $C_{8}H_{8}O_{3}$ Total number of atoms $N = 8(\text{C}) + 8(\text{H}) + 3(\text{O}) = 19$ Number of rings $R = 1$ (benzene ring) $$\sigma = N + R - 1 = 19 + 1 - 1 = 19$$ | Chemistry 10th JEE |
Determine the systematic IUPAC name for the following organic compound:
$$\text{CH}_3 - \text{CH}_2 - \underset{\text{CH}_3}{\underset{|}{\text{CH}}} - \underset{\begin{array}{c} \text{H}_3\text{C} - \text{C} - \text{CH}_3 \\ | \\ \text{CH}_3 \end{array}}{\underset{|}{\text{CH}}} - \text{CH}_2 - \text{CH}_2 - \underse... | **Final Answer:** 4-tert-butyl-3,7-dimethylnonane
$ ext{Structure: } CH_{3}-CH_{2}-CH(CH_{3})-CH(t ext{-Bu})-CH_{2}-CH_{2}-CH(C_{2}H_{5})-CH_{3}$
$ ext{Step 1: Find the longest carbon chain.}$
$ ext{Possible chain A (8C): } C_{1}-C_{2}-C_{3}-C_{4}-C_{5}-C_{6}-C_{7}-C_{8} = 8 ext{ carbons (octane)}$
$ ext{Possible ... | Chemistry 10th JEE |
Consider the two hydrocarbons $n$-pentane ($CH_3CH_2CH_2CH_2CH_3$) and $2$-methylbutane ($CH_3CH(CH_3)CH_2CH_3$). Identify the specific type of structural isomerism they exhibit and explain how their carbon chain arrangements differ. | **Final Answer:** Chain Isomerism; $n$-pentane is a straight-chain hydrocarbon while $2$-methylbutane is a branched-chain hydrocarbon. Molecular formula of $n$-pentane: $CH_{3}CH_{2}CH_{2}CH_{2}CH_{3} \rightarrow C_{5}H_{12}$ Molecular formula of $2$-methylbutane: $CH_{3}CH(CH_{3})CH_{2}CH_{3} \rightarrow C_{5}H_{12}$ ... | Chemistry 10th JEE |
Categorize each of the following organic reactions into one of these four types: **Addition**, **Substitution**, **Neutralization**, or **Esterification**.
a) $C_2H_5OH + CH_3COOH \xrightarrow{H^+} CH_3COOC_2H_5 + H_2O$
b) $CH_2=CH-CH_3 + H_2 \xrightarrow{Ni} CH_3-CH_2-CH_3$
c) $C_2H_6 + Cl_2 \xrightarrow{\text{Sunlig... | **Final Answer:** (a) Esterification, (b) Addition, (c) Substitution, (d) Neutralization For (a): $\text{Alcohol} + \text{Carboxylic Acid} \xrightarrow{H^{+}} \text{Ester} + H_{2}O \implies \text{Esterification}$ For (b): $R-CH=CH_{2} + H_{2} \xrightarrow{Ni} R-CH_{2}CH_{3} \implies \text{Addition}$ For (c): $C_{2}H_{6... | Chemistry 10th JEE |
The number of carbon compounds is estimated to be more than the compounds of all other elements put together. Explain the two characteristic properties of the carbon atom—namely tetravalency and catenation—that lead to this remarkable versatility. | **Final Answer:** The unique versatility of carbon is due to its tetravalency (forming 4 covalent bonds) and catenation (the ability to form long stable chains and rings). Carbon atomic number $Z=6$. Electronic configuration: $1s^{2} 2s^{2} 2p^{2}$. Valence electrons = $4$. Tetravalency: Sharing $4$ valence electrons $... | Chemistry 10th JEE |
Define the term allotropy and provide a comprehensive list of the various allotropic forms of carbon, distinguishing between crystalline and amorphous types. | **Final Answer:** Allotropy is the property of an element to exist in multiple physical forms with distinct properties. Carbon's crystalline allotropes are Diamond, Graphite, and Fullerenes; its amorphous allotropes include Coal, Coke, Charcoal, Lampblack, and Gas Carbon. $\text{Definition: Allotropy} \iff \text{Elemen... | Chemistry 10th JEE |
Identify and explain the diverse industrial and scientific uses of diamond, relating these applications to its unique physical properties such as its extreme hardness and high refractive index. | **Final Answer:** Diamond's $sp^{3}$ tetrahedral structure results in extreme hardness ($10$ Mohs) for industrial tools, high thermal conductivity ($2000 \, \text{W/m· K}$) for electronics, and high refractive index ($n=2.42$) for optical brilliance. Hardness Property: $sp^{3}$ hybridization $\rightarrow$ 3D covalent n... | Chemistry 10th JEE |
Define the term "Organic Compound." Furthermore, identify the first organic compound ever synthesized in a laboratory setting from an inorganic precursor and state the name of that precursor. | **Final Answer:** Organic compounds are hydrocarbons and their derivatives. The first synthesized organic compound is Urea ($NH_{2}CONH_{2}$), prepared from Ammonium cyanate ($NH_{4}CNO$). $\text{Organic Compound} = \text{Hydrocarbons and their derivatives}$ $\text{First Synthesized Organic Compound} = NH_{2}CONH_{2} \... | Chemistry 10th JEE |
What is the SI unit of mass? How is it defined? | The SI (International System of Units) base unit for mass is the kilogram. The symbol for the kilogram is kg. The kilogram is defined by taking the fixed numerical value of the Planck constant $$h$$ to be $$6.62607015 \times 10^{-34}$$ when expressed in the unit J⋅s. This unit, J⋅s, is equivalent to kg⋅m²⋅s⁻¹, where th... | Chemistry 11th |
Calculate the amount of water (g) produced by the combustion of 16 g of methane. | Write the balanced chemical equation for the combustion of methane: $${CH_4 + 2O_2 -> CO_2 + 2H_2O}$$. This shows a 1:2 mole ratio between methane and water. Convert the mass of methane ($${CH_4}$$) to moles using its molar mass ($$M \approx 16.0 \text{ g/mol}$$). The formula is $$n = \frac{m}{M}$$. $$n_{{CH_4}} = \fra... | Chemistry 11th |
How many seconds are there in 2 days? | The given time is 2 days. We need to convert this to seconds using known conversion factors. The conversion factors are: 1 day = 24 hours, 1 hour = 60 minutes, and 1 minute = 60 seconds. The formula is $$t_{seconds} = t_{days} \times \frac{24 \text{ hours}}{1 \text{ day}} \times \frac{60 \text{ minutes}}{1 \text{ hour}... | Chemistry 11th |
50.0 kg of $\mathrm{N}_{2}(\mathrm{~g})$ and 10.0 kg of $\mathrm{H}_{2}(\mathrm{~g})$ are mixed to produce $\mathrm{NH}_{3}(\mathrm{~g})$. Calculate the amount of $\mathrm{NH}_{3}(\mathrm{~g})$ formed. Identify
the limiting reagent in the production of $\mathrm{NH}_{3}$ in this situation. | The balanced chemical equation is $\mathrm{N}_{2}(\mathrm{~g}) + 3\mathrm{H}_{2}(\mathrm{~g}) \rightarrow 2\mathrm{NH}_{3}(\mathrm{~g})$. The given masses are 50.0 kg of $\mathrm{N}_{2}$ and 10.0 kg of $\mathrm{H}_{2}$. Convert the mass of each reactant to moles using their molar masses ($\mathrm{N}_{2}$ = 28.02 g/mol,... | Chemistry 11th |
How much copper can be obtained from 100 g of copper sulphate ( $\mathrm{CuSO}_{4}$ )? | First, calculate the molar mass of copper sulphate ($\mathrm{CuSO}_{4}$). The relevant atomic masses are Cu = 63.5 u, S = 32 u, and O = 16 u. The molar mass of $\mathrm{CuSO}_{4}$ is the sum of the atomic masses of its constituent atoms. $$M(\mathrm{CuSO}_{4}) = 63.5 + 32 + 4(16) = 159.5 \text{ g/mol}$$ The mass of cop... | Chemistry 11th |
In three moles of ethane $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)$, calculate the following:\
(i) Number of moles of carbon atoms.\
(ii) Number of moles of hydrogen atoms.\
(iii) Number of molecules of ethane. | The chemical formula for ethane is $${C_2H_6}$$. This indicates that one mole of ethane contains 2 moles of carbon atoms and 6 moles of hydrogen atoms. We are given 3 moles of ethane. To find the moles of carbon atoms, multiply the moles of ethane by the number of carbon atoms per molecule: $$Moles\ of\ C = 3\ moles\ {... | Chemistry 11th |
If the density of methanol is $0.793 \mathrm{~kg} \mathrm{~L}^{-1}$, what is its volume needed for making 2.5 L of its 0.25 M solution? | First, calculate the moles of methanol required. The molar mass of methanol ($${CH_3OH}$$) is 32.04 g/mol. The desired volume of the solution is 2.5 L and the molarity is 0.25 M. Use the molarity formula to find the moles ($$n$$) of solute: $$n = Molarity \times Volume_{solution}$$. $$n = 0.25 \frac{mol}{L} \times 2.5 ... | Chemistry 11th |
How many significant figures are present in the following?\
(i) 0.0025\
(ii) 208\
(iii) 5005\
(iv) 126,000\
(v) 500.0\
(vi) 2.0034 | Identify the rules for significant figures. Non-zero digits are significant. Zeros between non-zero digits are significant. Leading zeros are not significant. Trailing zeros are significant only if a decimal point is present. For 0.0025, the leading zeros are not significant, so there are 2 significant figures (2, 5). ... | Chemistry 11th |
Dinitrogen and dihydrogen react with each other to produce ammonia according to the following chemical equation:
$\mathrm{N}_{2}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{NH}_{3}(\mathrm{~g})$\
(i) Calculate the mass of ammonia produced if $2.00 \times 10^{3} \mathrm{~g}$ dinitrogen reacts with $1.... | First, balance the chemical equation and calculate the initial moles of each reactant. The balanced equation is $$\mathrm{N}_{2}(\mathrm{g})+3\mathrm{H}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NH}_{3}(\mathrm{g})$$. Moles of $$\mathrm{N}_{2}$$ = $$\frac{2.00 \times 10^{3} \mathrm{g}}{28.02 \mathrm{g/mol}} = 71.38 \mathrm... | Chemistry 11th |
Convert the following into basic units:\
(i) $\quad 28.7 \mathrm{pm}$\
(ii) 15.15 pm\
(iii) 25365 mg | Identify the given quantities and their target basic SI units. For length (pm), the basic unit is the meter (m). For mass (mg), the basic unit is the kilogram (kg). State the necessary conversion factors. For length: $$1 \text{ pm} = 10^{-12} \text{ m}$$. For mass: $$1 \text{ mg} = 10^{-6} \text{ kg}$$. Convert the len... | Chemistry 11th |
Use the data given in the following table to calculate the molar mass of naturally occurring argon isotopes: Isotope | Isotopic molar mass | Abundance\
(i) $^{36}Ar$ | 35.96755 g/mol | 0.337%\
(ii) $^{38}Ar$ | 37.96272 g/mol | 0.063%\
(iii) $^{40}Ar$ | 39.9624 g/mol | 99.600% | The given data includes the isotopic molar mass and percent abundance for each argon isotope: $^{36}Ar$ (35.96755 g/mol, 0.337%), $^{38}Ar$ (37.96272 g/mol, 0.063%), and $^{40}Ar$ (39.9624 g/mol, 99.600%). The formula for average molar mass is the sum of each isotope's mass multiplied by its fractional abundance: $$M_{... | Chemistry 11th |
A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives 3.38 g carbon dioxide, 0.690 g of water and no other products. A volume of 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g . Calculate\
(i) empirical formula,\
(ii) molar mass of the gas, and\
(iii) ... | First, calculate the moles of Carbon and Hydrogen from the combustion products. Moles C = $$3.38 \text{ g } {CO_2} \times \frac{1 \text{ mol C}}{44.01 \text{ g } {CO_2}} = 0.0768 \text{ mol}$$. Moles H = $$0.690 \text{ g } {H_2O} \times \frac{2 \text{ mol H}}{18.02 \text{ g } {H_2O}} = 0.0766 \text{ mol}$$. The mole ra... | Chemistry 11th |
How does chemistry contribute to the national economy and improvement of quality of life? | Chemistry drives economic growth through industries like pharmaceuticals, agriculture, and manufacturing. It creates jobs and produces goods for domestic use and export. For example, the synthesis of fertilizers like ammonia ($${NH_3}$$) boosts crop yields, supporting the food industry. In healthcare, chemistry is fund... | Chemistry 11th |
What role does chemistry play in environmental protection? Give examples of how chemistry has helped address environmental issues. | Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It involves understanding how the uncontaminated environment works, and which naturally occurring chemicals are present, at what concentrations, and with what effects. A key role of chemistry is monit... | Chemistry 11th |
Compare the arrangement of particles in solid, liquid and gaseous states of matter. | In a solid, particles are tightly packed in a fixed, regular, and orderly pattern, often a crystal lattice. They vibrate about their fixed positions but do not move from place to place. In a liquid, particles are closely packed but are not held in fixed positions. They are randomly arranged and can move or slide past o... | Chemistry 11th |
Distinguish between homogeneous and heterogeneous mixtures with examples. | A mixture is a substance made by combining two or more different materials without a chemical reaction occurring between them. A homogeneous mixture has a uniform composition and properties throughout. The individual components are not visually distinguishable. It exists in a single phase. Examples include saltwater, a... | Chemistry 11th |
How would you classify sugar solution, brass, and air as homogeneous or heterogeneous mixtures? Justify your answer. | Define the types of mixtures. A homogeneous mixture has a uniform composition and properties throughout. A heterogeneous mixture has a non-uniform composition where components are often visibly distinct. Analyze the sugar solution. When sugar dissolves in water, its particles distribute evenly at the molecular level. T... | Chemistry 11th |
Why is it necessary to have a standard system of units for measurement in science? | A standard system of units ensures clear and unambiguous communication among scientists globally. It eliminates confusion that would arise from using different local or regional measurement systems. It is essential for the reproducibility of experiments. For scientific findings to be validated, other researchers must b... | Chemistry 11th |
How is the mass of a substance determined in the laboratory? What instrument is used for accurate measurement? | The mass of a substance is determined by a process called weighing. The primary instrument used for accurate mass measurement in a laboratory is an electronic balance or a more sensitive analytical balance. To measure the mass, a container (like a weighing boat or beaker) is placed on the balance pan, and the balance i... | Chemistry 11th |
Define density. How is it calculated and what are its SI units? | Density is a physical property of a substance defined as its mass per unit of volume. The formula to calculate density ($$\rho$$) is the mass ($$m$$) of an object divided by its volume ($$V$$): $$\rho = \frac{m}{V}$$ The SI unit for mass is the kilogram (kg) and for volume is the cubic meter ($$\mathrm{m^3}$$). Therefo... | Chemistry 11th |
The density of mercury is $13.6 \mathrm{~g} \mathrm{~cm}^{-3}$. Express it in SI units. | The given density is $$13.6 \ \text{g/cm}^3$$. The SI unit for density is kilograms per cubic meter (kg/m³). The necessary conversion factors are $$1 \ \text{kg} = 1000 \ \text{g}$$ and $$1 \ \text{m} = 100 \ \text{cm}$$. From this, we derive the volume conversion: $$1 \ \text{m}^3 = (100 \ \text{cm})^3 = 10^6 \ \text{... | Chemistry 11th |
Convert the following temperatures:\
(a) $25^{\circ}\mathrm{C}$ to Kelvin\
(b) 373 K to Celsius | To convert from Celsius to Kelvin, use the formula $$K = {^{\circ}\mathrm{C}} + 273.15$$. Substitute the given Celsius temperature: $$K = 25 + 273.15 = 298.15 \text{ K}$$. To convert from Kelvin to Celsius, use the formula $${^{\circ}\mathrm{C}} = K - 273.15$$. Substitute the given Kelvin temperature: $${^{\circ}\mathr... | Chemistry 11th |
How do you perform addition and subtraction of numbers expressed in scientific notation? | First, ensure all numbers have the same exponent for the power of 10. Adjust the coefficient (the decimal part) and the exponent as needed. For instance, $$2.5 \times 10^3$$ can be written as $$0.25 \times 10^4$$. Once the exponents are identical, add or subtract the coefficients. The result of the addition or subtract... | Chemistry 11th |
State the rules for determining the number of significant figures in a measurement. | Non-zero digits (1-9) are always significant. For example, 487 has three significant figures. Zeros located between non-zero digits are significant. For example, 606 has three significant figures. Leading zeros (zeros at the beginning of a number) are not significant. For example, 0.05 has one significant figure. Trail... | Chemistry 11th |
State the Law of Conservation of Mass. Who proposed this law and based on what observations? | The Law of Conservation of Mass states that in a closed system, mass is neither created nor destroyed during a chemical reaction. The total mass of the reactants equals the total mass of the products. This law was proposed by the French chemist Antoine Lavoisier in the late 18th century. Lavoisier's conclusion was base... | Chemistry 11th |
Why is the Law of Definite Proportions also called the Law of Constant Composition? | The Law of Definite Proportions states that a chemical compound always contains its component elements in a fixed ratio by mass, regardless of its source or method of preparation. The Law of Constant Composition states that any given pure chemical compound will always have the same elemental composition by mass. Both l... | Chemistry 11th |
State Gay Lussac's Law of Gaseous Volumes. Under what conditions is this law valid? | Gay-Lussac's Law of Gaseous Volumes states that when gases react together to form other gases, the volumes of the reacting gases and the products bear a simple whole-number ratio to one another. For example, in the reaction:
$$2\text{H}_2(g) + \text{O}_2(g) \rightarrow 2\text{H}_2\text{O}(g)$$
two volumes of hydrogen g... | Chemistry 11th |
How did Gay Lussac's Law of Gaseous Volumes lead to the development of Avogadro's hypothesis? | Gay-Lussac's Law established that reacting gases and their gaseous products do so in simple whole-number volume ratios. For example, 2 volumes of hydrogen gas react with 1 volume of oxygen gas to produce 2 volumes of water vapor. This observation conflicted with Dalton's Atomic Theory, which assumed indivisible atoms a... | Chemistry 11th |
How did Avogadro's Law explain the observations of Gay Lussac regarding combining volumes of gases? | Gay-Lussac's Law observed that when gases react, their volumes are in simple whole-number ratios. For example, 2 volumes of hydrogen react with 1 volume of oxygen to produce 2 volumes of water vapor. Avogadro's Law states that equal volumes of gases at the same temperature and pressure contain an equal number of molecu... | Chemistry 11th |
Why is the atomic mass of most elements not a whole number in the periodic table? | The mass of an individual atom is determined by its protons and neutrons. The sum of protons and neutrons is the mass number, which is always a whole number. However, most elements exist in nature as a mixture of isotopes. Isotopes are atoms of the same element that have the same number of protons but different numbers... | Chemistry 11th |
Calculate the molecular mass of sulphuric acid ($\mathrm{H}_2\mathrm{SO}_4$). | Identify the number of atoms for each element in $$\mathrm{H}_2\mathrm{SO}_4$$: 2 Hydrogen (H), 1 Sulfur (S), and 4 Oxygen (O). The formula for molecular mass is the sum of the atomic masses of all constituent atoms. The standard atomic masses are H ≈ 1.008 u, S ≈ 32.06 u, and O ≈ 16.00 u. Substitute the values into th... | Chemistry 11th |
What is formula mass? For which type of compounds is it used? | Formula mass is the sum of the average atomic masses of all the atoms in a compound's empirical formula. The atomic mass for each element is obtained from the periodic table and is measured in atomic mass units (amu). Formula mass is the term used for ionic compounds. Ionic compounds form a crystal lattice structure, n... | Chemistry 11th |
Define mole. Why is mole concept important in chemistry? | A mole is the SI unit for the amount of a substance. It is defined as exactly $$6.02214076 \times 10^{23}$$ elementary entities (such as atoms, molecules, ions, or electrons). This specific number is known as Avogadro's number ($$N_A$$). It was chosen so that the mass of one mole of a chemical compound in grams is nume... | Chemistry 11th |
Calculate the number of atoms in 4.6 g of sodium (Atomic mass of Na = 23 u). | The given mass of sodium ($$m$$) is 4.6 g. The atomic mass of sodium is 23 u, so its molar mass ($$M$$) is 23 g/mol. Avogadro's number ($$N_A$$) is $$6.022 \times 10^{23}$$ atoms/mol. The number of atoms ($$N$$) is found by first calculating the number of moles ($$n$$) and then multiplying by Avogadro's number. The com... | Chemistry 11th |
What is empirical formula? How does it differ from molecular formula? | The empirical formula represents the simplest whole-number ratio of atoms of each element present in a compound. The molecular formula shows the actual number of atoms of each element in a single molecule of that compound. The molecular formula is always a whole-number multiple of the empirical formula. This relationsh... | Chemistry 11th |
What are stoichiometric coefficients? What do they represent in a balanced equation? | Stoichiometric coefficients are the numbers placed in front of chemical formulas in a balanced chemical equation to indicate the relative number of moles of each substance. They ensure that the number of atoms of each element is conserved on both the reactant and product sides of the equation, satisfying the Law of Con... | Chemistry 11th |
In a reaction between 5 moles of hydrogen and 3 moles of oxygen to form water, identify the limiting reagent and calculate the moles of water formed. | First, write the balanced chemical equation for the reaction: $${2H_2} + {O_2} \rightarrow 2{H_2O}$$. This establishes the stoichiometric ratio of 2 moles of hydrogen to 1 mole of oxygen. Next, calculate the amount of product ($${H_2O}$$) that can be formed from each reactant. For hydrogen: $$5 \text{ mol } {H_2} \time... | Chemistry 11th |
A solution is prepared by dissolving 10 g of sugar in 90 g of water. Calculate the mass percent of sugar in the solution. | The given data is: Mass of solute (sugar) = 10 g and Mass of solvent (water) = 90 g. The formula for mass percent is: $$\text{Mass Percent} = \frac{\text{Mass of solute}}{\text{Mass of solution}} \times 100\%$$. The mass of the solution is the sum of the mass of the solute and the mass of the solvent. First, calculate ... | Chemistry 11th |
A solution contains 2 moles of ethanol and 8 moles of water. Calculate the mole fraction of each component. | The given data is: moles of ethanol ($$n_{ethanol}$$) = 2 mol, and moles of water ($$n_{water}$$) = 8 mol. The formula for mole fraction ($$X_i$$) is $$X_i = \frac{n_i}{n_{total}}$$, where $$n_{total}$$ is the sum of the moles of all components. First, calculate the total moles: $$n_{total} = n_{ethanol} + n_{water} = ... | Chemistry 11th |
Calculate the molarity of a solution prepared by dissolving 5.85 g of NaCl in 500 mL of solution. (Molar mass of NaCl = 58.5 g) | First, calculate the number of moles of the solute, sodium chloride ($${NaCl}$$), using its mass and molar mass. The formula for moles is $$moles = \frac{\text{mass}}{\text{molar mass}}$$. Substituting the given values: $$moles = \frac{5.85 \text{ g}}{58.5 \text{ g/mol}} = 0.1 \text{ mol}$$ Next, convert the volume of ... | Chemistry 11th |
State Avogadro's Law. What distinction did Avogadro make between atoms and molecules? | Avogadro's Law states that equal volumes of all gases, at the same temperature and pressure, contain the same number of molecules. The mathematical expression for Avogadro's Law is $$V \propto n$$, or $$\frac{V_1}{n_1} = \frac{V_2}{n_2}$$, where $$V$$ is the volume and $$n$$ is the number of moles of the gas. Avogadro ... | Chemistry 11th |
A piece of metal is 3 inch (represented by in) long. What is its length in cm? | The given length is 3 inches. The conversion factor between inches and centimeters is $$1 \text{ in} = 2.54 \text{ cm}$$. The formula to convert inches to centimeters is: Length in cm = Length in inches $$ \times \frac{2.54 \text{ cm}}{1 \text{ in}}$$. Substitute the given value into the formula: $$3 \text{ in} \times ... | Chemistry 11th |
A jug contains 2 L of milk. Calculate the volume of the milk in $\mathrm{m}^{3}$. | The given volume of milk is 2 L. The conversion factor between liters and cubic meters is $$1 \ \mathrm{L} = 0.001 \ \mathrm{m}^3$$. Multiply the volume in liters by the conversion factor: $$V = 2 \ \mathrm{L} \times \frac{0.001 \ \mathrm{m}^3}{1 \ \mathrm{L}} = 0.002 \ \mathrm{m}^3$$. The volume of the milk is 0.002 c... | Chemistry 11th |
Calculate the molecular mass of glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ molecule. | The chemical formula for glucose is $$\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$$. The required atomic masses are: Carbon ($$\mathrm{C}$$) is 12.011 amu, Hydrogen ($$\mathrm{H}$$) is 1.008 amu, and Oxygen ($$\mathrm{O}$$) is 15.999 amu. The molecular mass is the sum of the atomic masses of all atoms in the molecule... | Chemistry 11th |
A compound contains 4.07% hydrogen, $24.27 %$ carbon and $71.65 %$ chlorine. Its molar mass is 98.96 g . What are its empirical and molecular formulas? | Assume a 100 g sample, so the percentages convert directly to grams: 4.07 g H, 24.27 g C, and 71.65 g Cl. Convert the mass of each element to moles by dividing by its atomic mass. Moles of H: $$\frac{4.07 \text{ g}}{1.008 \text{ g/mol}} = 4.04 \text{ mol}$$. Moles of C: $$\frac{24.27 \text{ g}}{12.01 \text{ g/mol}} = 2... | Chemistry 11th |
How many moles of methane are required to produce $22 \mathrm{~g} \mathrm{CO}_{2}(\mathrm{~g})$ after combustion? | First, write the balanced chemical equation for the combustion of methane. The equation is:
$$\text{CH}_4(g) + 2\text{O}_2(g) \rightarrow \text{CO}_2(g) + 2\text{H}_2\text{O}(g)$$
This indicates a 1:1 molar ratio between $\text{CH}_4$ and $\text{CO}_2$. Next, calculate the molar mass of carbon dioxide ($\text{CO}_2$). ... | Chemistry 11th |
A solution is prepared by adding 2 g of a substance A to 18 g of water. Calculate the mass per cent of the solute. | The mass of the solute (substance A) is 2 g and the mass of the solvent (water) is 18 g. The total mass of the solution is the sum of the mass of the solute and the solvent. The formula for the mass per cent of a solute is: $$Mass \% = (\frac{\text{Mass of Solute}}{\text{Mass of Solution}}) \times 100\%$$ First, calcul... | Chemistry 11th |
Calculate the molarity of NaOH in the solution prepared by dissolving its 4 g in enough water to form 250 mL of the solution. | The given data is: Mass of NaOH = 4 g, Volume of solution = 250 mL. First, calculate the moles of NaOH using the formula: $$\text{Moles} = \frac{\text{Mass}}{\text{Molar Mass}}$$. The molar mass of NaOH is $$23 + 16 + 1 = 40$$ g/mol. Substitute the values to find the moles: $$\text{Moles of NaOH} = \frac{4 \text{ g}}{4... | Chemistry 11th |
The density of 3 M solution of NaCl is $1.25 \mathrm{~g} \mathrm{~mL}^{-1}$. Calculate the molality of the solution. | Assume 1 L (1000 mL) of the solution. Given the molarity is 3 M, this volume contains 3 moles of NaCl. The molar mass of NaCl is 58.5 g/mol. Calculate the mass of the solute (NaCl) and the total mass of the solution. Mass of solute = $$3 \text{ mol} \times 58.5 \text{ g/mol} = 175.5 \text{ g}$$. Mass of solution = $$1.... | Chemistry 11th |
Calculate the molar mass of the following:\
(i) $\mathrm{H}_{2} \mathrm{O}$\
(ii) $\mathrm{CO}_{2}$\
(iii) $\mathrm{CH}_{4}$ | First, identify the atomic masses of the constituent elements from the periodic table. The approximate atomic masses are: H = 1.0 g/mol, C = 12.0 g/mol, and O = 16.0 g/mol. For water ($$\mathrm{H_2O}$$), sum the masses of two hydrogen atoms and one oxygen atom. The calculation is $$ (2 \times 1.0) + (1 \times 16.0) = 1... | Chemistry 11th |
Calculate the mass per cent of different elements present in sodium sulphate $\left(\mathrm{Na}_{2} \mathrm{SO}_{4}\right)$. | First, calculate the molar mass of sodium sulphate ($$\mathrm{Na}_{2}\mathrm{SO}_{4}$$). The atomic masses are Na = 23.0 u, S = 32.0 u, and O = 16.0 u. Molar mass of $$\mathrm{Na}_{2}\mathrm{SO}_{4} = (2 \times 23.0) + (1 \times 32.0) + (4 \times 16.0) = 142.0 \text{ g/mol}$$. The formula for mass percent of an element... | Chemistry 11th |
Determine the empirical formula of an oxide of iron, which has $69.9 %$ iron and 30.1 % dioxygen by mass. | Assume a 100 g sample. This means there are 69.9 g of iron (Fe) and 30.1 g of oxygen (O). The molar mass of Fe is 55.85 g/mol and O is 16.00 g/mol. Convert the mass of each element to moles using the formula $$n = \frac{m}{M}$$, where $$n$$ is moles, $$m$$ is mass, and $$M$$ is molar mass. Calculate the moles of each e... | Chemistry 11th |
Calculate the amount of carbon dioxide that could be produced when\
(i) 1 mole of carbon is burnt in air.\
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.\
(iii) 2 moles of carbon are burnt in 16 g of dioxygen. | The balanced chemical equation for the combustion of carbon is $$C(s) + O_2(g) \rightarrow CO_2(g)$$. This indicates a 1:1 molar ratio between carbon, dioxygen, and carbon dioxide. For case (i), burning in air means oxygen is in excess. Carbon is the limiting reactant. Therefore, 1 mole of carbon produces 1 mole of $$\... | Chemistry 11th |
Calculate the mass of sodium acetate $\left(\mathrm{CH}_{3} \mathrm{COONa}\right)$ required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is $82.0245 \mathrm{~g} \mathrm{~mol}^{-1}$. | Given data: Volume $$V = 500$$ mL, Molarity $$M = 0.375$$ M, and Molar Mass of $$\mathrm{CH}_{3}\mathrm{COONa}$$ is 82.0245 g/mol. The formula to find the mass of the solute is $$Mass = Molarity \times Volume \times Molar \ Mass$$. Convert the volume to Liters ($$500 \ mL = 0.500 \ L$$) and substitute the values: $$Mas... | Chemistry 11th |
Calculate the concentration of nitric acid in moles per litre in a sample which has a density, $1.41 \mathrm{~g} \mathrm{~mL}^{-1}$ and the mass per cent of nitric acid in it being 69%. | First, calculate the mass of 1 L (1000 mL) of the solution using the given density. $$Mass = Density \times Volume = 1.41 \frac{g}{mL} \times 1000 mL = 1410 g$$ Next, determine the mass of nitric acid ($${HNO_3}$$) in the solution using the mass percentage. $$Mass_{{HNO_3}} = 0.69 \times 1410 g = 972.9 g$$ Then, calcul... | Chemistry 11th |
Determine the molecular formula of an oxide of iron, in which the mass per cent of iron and oxygen are 69.9 and 30.1, respectively. | Assume a 100 g sample. This means there are 69.9 g of iron (Fe) and 30.1 g of oxygen (O). Convert the mass of each element to moles using their molar masses (Fe = 55.85 g/mol, O = 16.00 g/mol). The formula is $$moles = \frac{mass}{molar \ mass}$$. Moles of Fe = $$\frac{69.9 \ g}{55.85 \ g/mol} = 1.25 \ mol$$. Moles of ... | Chemistry 11th |
Calculate the atomic mass (average) of chlorine using the following data:
$$
\begin{array}{|c|c|c|}
\hline
\text{Isotope} & \% \text{ Natural Abundance} & \text{Molar Mass} \\
\hline
{}^{35}\mathrm{Cl} & 75.77 & 34.9689 \\
\hline
{}^{37}\mathrm{Cl} & 24.23 & 36.9659 \\
\hline
\end{array}
$$ | The given data includes two isotopes: $$^{35}\mathrm{Cl}$$ with a natural abundance of 75.77% and a molar mass of 34.9689 amu, and $$^{37}\mathrm{Cl}$$ with a natural abundance of 24.23% and a molar mass of 36.9659 amu. The formula for average atomic mass is the sum of the products of each isotope's mass and its fracti... | Chemistry 11th |
What is the concentration of sugar $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ in $\mathrm{mol} \mathrm{L}^{-1}$ if its 20 g are dissolved in enough water to make a final volume up to 2 L ? | First, calculate the molar mass ($$M$$) of sugar, $$\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$$. The atomic masses are C=12.01 g/mol, H=1.01 g/mol, and O=16.00 g/mol. $$M = (12 \times 12.01) + (22 \times 1.01) + (11 \times 16.00) = 342.34$$ g/mol. Next, calculate the number of moles ($$n$$) of sugar using the giv... | Chemistry 11th |
Pressure is determined as force per unit area of the surface. The SI unit of pressure, pascal is as shown below:
$1 \mathrm{~Pa}=1 \mathrm{Nm}^{-2}$
If mass of air at sea level is $1034 \mathrm{~g} \mathrm{~cm}^{-2}$, calculate the pressure in pascal. | First, convert the given mass per unit area from g cm⁻² to the SI unit of kg m⁻². The acceleration due to gravity, $$g$$, is approximately $$9.8 \text{ m s}^{-2}$$. The mass per unit area is $$ \frac{m}{A} = 1034 \frac{\text{g}}{\text{cm}^2} \times \frac{1 \text{ kg}}{1000 \text{ g}} \times \frac{(100 \text{ cm})^2}{(1... | Chemistry 11th |
Match the following prefixes with their multiples:\
(i) micro - $10^{6}$\
(ii) deca - $10^{9}$\
(iii) mega - $10^{-6}$\
(iv) giga - $10^{-15}$\
(v) femto - 10 | Recall the standard definitions for the given SI prefixes. Micro ($$\mu$$) corresponds to a multiple of $$10^{-6}$$. Deca (da) corresponds to a multiple of $$10^1$$ or 10. Mega (M) corresponds to a multiple of $$10^6$$. Giga (G) corresponds to a multiple of $$10^9$$. Femto (f) corresponds to a multiple of $$10^{-15}$$.... | Chemistry 11th |
What do you mean by significant figures? | Significant figures in a number are the digits that carry meaning contributing to its measurement precision. This includes all certain digits plus one estimated or uncertain digit. Rule 1: All non-zero digits are significant. For example, the number 487 has three significant figures. Rule 2: Zeros between non-zero digi... | Chemistry 11th |
A sample of drinking water was found to be severely contaminated with chloroform, $\mathrm{CHCl}_{3}$, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).\
(i) Express this in per cent by mass.\
(ii) Determine the molality of chloroform in the water sample. | The concentration is 15 ppm (parts per million) by mass. This means there are 15 g of chloroform ($\mathrm{CHCl}_{3}$) in every $$10^6$$ g of the solution. To find the percent by mass, use the formula: $$\text{Percent by mass} = \frac{\text{mass of solute}}{\text{mass of solution}} \times 100$$. Substituting the values... | Chemistry 11th |
Express the following in the scientific notation:\
(i) 0.0048\
(ii) 234,000\
(iii) 8008\
(iv) 500.0\
(v) 6.0012 | Scientific notation is expressed in the form $$a \times 10^n$$, where $$a$$ is a number between 1 and 10, and $$n$$ is an integer exponent. For 0.0048, move the decimal point 3 places to the right to get 4.8. Since the original number is less than 1, the exponent is negative. The result is $$4.8 \times 10^{-3}$$. For 2... | Chemistry 11th |
Round up the following upto three significant figures:\
(i) $\quad 34.216$\
(ii) 10.4107\
(iii) 0.04597\
(iv) 2808 | For $$34.216$$, the fourth digit is 1, which is less than 5. The third digit, 2, remains unchanged. The number is rounded to $$34.2$$. For $$10.4107$$, the fourth digit is 1, which is less than 5. The third digit, 4, remains unchanged. The number is rounded to $$10.4$$. For $$0.04597$$, the leading zeros are not signif... | Chemistry 11th |
The following data are obtained when dinitrogen and dioxygen react together to form different compounds: Mass of dinitrogen | Mass of dioxygen\
(i) 14 g | 16 g\
(ii) 14 g | 32 g\
(iii) 28 g | 32 g\
(iv) 28 g | 80 g\
(a) Which law of chemical combination is obeyed by the above experimental data? Give its statement.\
(b)... | To identify the chemical law, we fix the mass of one reactant, dinitrogen, to 14 g and find the corresponding masses of dioxygen. For the given data points, the masses of dioxygen are 16 g, 32 g, 16 g (from 32 g O / 28 g N), and 40 g (from 80 g O / 28 g N). The different masses of dioxygen that combine with a fixed mas... | Chemistry 11th |
If the speed of light is $3.0 \times 10^{8} \mathrm{~m} \mathrm{~s}^{-1}$, calculate the distance covered by light in 2.00 ns . | The given values are the speed of light, $$c = 3.0 \times 10^{8} \mathrm{~m} \mathrm{~s}^{-1}$$, and the time, $$t = 2.00 \mathrm{~ns}$$. First, convert the time from nanoseconds to seconds: $$t = 2.00 \times 10^{-9} \mathrm{~s}$$. The formula relating distance, speed, and time is $$d = c \times t$$. Substitute the giv... | Chemistry 11th |
In a reaction
$\mathrm{A}+\mathrm{B}_{2} \rightarrow \mathrm{AB}_{2}$
Identify the limiting reagent, if any, in the following reaction mixtures.\
(i) 300 atoms of $\mathrm{A}+200$ molecules of B\
(ii) $\quad 2 \mathrm{~mol} \mathrm{~A}+3 \mathrm{~mol} \mathrm{~B}$\
(iii) 100 atoms of $\mathrm{A}+100$ molecules of B\
(i... | The balanced equation is $$\mathrm{A}+\mathrm{B}_{2} \rightarrow \mathrm{AB}_{2}$$. The stoichiometric ratio of A to B₂ is 1:1. The limiting reagent is the reactant present in the smaller amount relative to this 1:1 ratio. We compare the given quantities for each mixture. (i) For 300 atoms of A and 200 molecules of B₂,... | Chemistry 11th |
How are $0.50 \mathrm{~mol} \mathrm{Na}_{2} \mathrm{CO}_{3}$ and $0.50 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}$ different? | The term $$0.50 \mathrm{~mol} \mathrm{Na}_{2} \mathrm{CO}_{3}$$ represents a specific quantity of the substance. A mole is a unit for the amount of a substance. The term $$0.50 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}$$ represents the concentration of a solution. The 'M' stands for molarity, which is defined as moles... | Chemistry 11th |
If 10 volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour would be produced? | First, write the balanced chemical equation for the reaction. Dihydrogen gas ($${H_2}$$) reacts with dioxygen gas ($${O_2}$$) to form water vapor ($${H_2O}$$). The balanced equation is $$2{H_2}(g) + {O_2}(g) \rightarrow 2{H_2O}(g)$$. According to Gay-Lussac's Law of Gaseous Volumes, the ratio of the volumes of reacting... | Chemistry 11th |
Which one of the following will have the largest number of atoms?\
(i) $\quad 1 \mathrm{~g} \mathrm{Au}(\mathrm{s})$\
(ii) $\quad 1 \mathrm{~g} \mathrm{Na}(\mathrm{s})$\
(iii) $\quad 1 \mathrm{~g} \mathrm{Li}(\mathrm{s})$\
(iv) 1 g of $\mathrm{Cl}_{2}(\mathrm{~g})$ | The number of atoms in a fixed mass of a substance is inversely proportional to its molar mass. To find the substance with the most atoms, we must find the one with the lowest molar mass per atom. The molar masses of the elements are approximately: Au = 197 g/mol, Na = 23 g/mol, and Li = 7 g/mol. The molar mass of a ch... | Chemistry 11th |
Calculate the molarity of a solution of ethanol in water, in which the mole fraction of ethanol is 0.040 (assume the density of water to be one). | The given information is the mole fraction of ethanol, $\chi_{\text{ethanol}} = 0.040$, and the density of the solvent (water) is 1.0 kg/L. We need to find the molarity (M). The relevant formulas are for mole fraction, $\chi_{\text{ethanol}} = \frac{n_{\text{ethanol}}}{n_{\text{ethanol}} + n_{\text{water}}}$, and molar... | Chemistry 11th |
What will be the mass of one ${ }^{12} \mathrm{C}$ atom in g ? | The molar mass of Carbon-12 ($${}^{12}\mathrm{C}$$) is defined as exactly 12 grams per mole. Avogadro's number ($$N_A$$) is $$6.022 \times 10^{23}$$ atoms per mole. The formula to find the mass of a single atom is the molar mass ($$M$$) divided by Avogadro's number ($$N_A$$). $$ \text{Mass of one atom} = \frac{M}{N_A} ... | Chemistry 11th |
How many significant figures should be present in the answer of the following calculations?\
(i) $\frac{0.02856 \times 298.15 \times 0.112}{0.5785}$\
(ii) $5 \times 5.364$\
(iii) $\quad 0.0125+0.7864+0.0215$ | For calculation (i), a multiplication and division problem, the result is limited by the term with the fewest significant figures. The numbers are $$0.02856$$ (4 sig figs), $$298.15$$ (5 sig figs), $$0.112$$ (3 sig figs), and $$0.5785$$ (4 sig figs). The minimum is 3. For calculation (ii), a multiplication problem, the... | Chemistry 11th |
Calculate the number of atoms in each of the following\
(i) 52 moles of Ar\
(ii) 52 u of He\
(iii) 52 g of He . | For 52 moles of Ar, the number of atoms is found by multiplying moles by Avogadro's number ($$N_A$$). $$N = 52 \times 6.022 \times 10^{23} = 3.131 \times 10^{25}$$ atoms. For 52 u of He, the mass of one He atom is 4 u. The number of atoms is the total mass divided by the mass of a single atom. Number of atoms = $$\frac... | Chemistry 11th |
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