QnA_All / answer_key.json
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[
{
"section": "A",
"question_number": "1(i)",
"answer": "b",
"marks": 1
},
{
"section": "A",
"question_number": "1(ii)",
"answer": "a",
"marks": 1
},
{
"section": "A",
"question_number": "1(iii)",
"answer": "c",
"marks": 1
},
{
"section": "A",
"question_number": "1(iv)",
"answer": "a",
"marks": 1
},
{
"section": "A",
"question_number": "1(v)",
"answer": "b",
"marks": 1
},
{
"section": "A",
"question_number": "1(vi)",
"answer": "c",
"marks": 1
},
{
"section": "A",
"question_number": "1(vii)",
"answer": "d",
"marks": 1
},
{
"section": "A",
"question_number": "1(viii)",
"answer": "b",
"marks": 1
},
{
"section": "A",
"question_number": "1(ix)",
"answer": "a",
"marks": 1
},
{
"section": "A",
"question_number": "1(x)",
"answer": "a",
"marks": 1
},
{
"section": "A",
"question_number": "1(xi)",
"answer": "b",
"marks": 1
},
{
"section": "A",
"question_number": "1(xii)",
"answer": "a",
"marks": 1
},
{
"section": "A",
"question_number": "1(xiii)",
"answer": "c",
"marks": 1
},
{
"section": "A",
"question_number": "1(xiv)",
"answer": "d",
"marks": 1
},
{
"section": "A",
"question_number": "1(xv)",
"answer": "a",
"marks": 1
},
{
"section": "A",
"question_number": "2(i)(a)",
"answer": "C¹⁴ is a radioisotope because of the instability of the nucleus. Used for carbon dating.",
"marks": 2
},
{
"section": "A",
"question_number": "2(i)(b)",
"answer": "Class II lever.",
"marks": 1
},
{
"section": "A",
"question_number": "2(ii)(a)",
"answer": "Centripetal",
"marks": 1
},
{
"section": "A",
"question_number": "2(ii)(b)",
"answer": "zero",
"marks": 1
},
{
"section": "A",
"question_number": "2(iii)",
"answer": "30 N",
"marks": 2
},
{
"section": "A",
"question_number": "2(iv)(a)",
"answer": "Mechanical advantage using a block and tackle system of 9 pulleys is 9 whereas the mechanical advantage of a single moveable pulley is 2.",
"marks": 1
},
{
"section": "A",
"question_number": "2(iv)(b)",
"answer": "Increase of number of pulley increases mechanical advantage.",
"marks": 1
},
{
"section": "A",
"question_number": "2(v)",
"answer": "4:1",
"marks": 2
},
{
"section": "A",
"question_number": "2(vi)(a)",
"answer": "Resistance decreases",
"marks": 1
},
{
"section": "A",
"question_number": "2(vi)(b)",
"answer": "Current (Intensity of light) increases as resistance decreases",
"marks": 1
},
{
"section": "A",
"question_number": "2(vii)",
"answer": "17:10",
"marks": 2
},
{
"section": "A",
"question_number": "3(i)(a)",
"answer": "In between optical centre and focus",
"marks": 1
},
{
"section": "A",
"question_number": "3(i)(b)",
"answer": "Because concave lens produces reduced size image.",
"marks": 1
},
{
"section": "A",
"question_number": "3(ii)",
"answer": "No. The geyser draws I = P/V = 1540/220 = 7A. Hence, 5A rated fuse will blow off for the geyser.",
"marks": 2
},
{
"section": "A",
"question_number": "3(iii)",
"answer": "1. Increasing the number of turns of the armature\n2. Increasing the applied battery e.m.f.",
"marks": 2
},
{
"section": "A",
"question_number": "3(iv)",
"answer": "165,000 J",
"marks": 2
},
{
"section": "A",
"question_number": "3(v)",
"answer": "₉₂U²³⁵ + ₀n¹ → ₅₆Ba¹⁴¹ + ₃₆Kr⁹² + 3₀n¹",
"marks": 2
},
{
"section": "B",
"question_number": "4(i)",
"answer": "f = 24 cm\nPower = 4.17 D",
"marks": 3
},
{
"section": "B",
"question_number": "4(ii)(a)",
"answer": "Microwave",
"marks": 1
},
{
"section": "B",
"question_number": "4(ii)(b)",
"answer": "X-rays",
"marks": 1
},
{
"section": "B",
"question_number": "4(ii)(c)",
"answer": "Both have same speed in vacuum",
"marks": 1
},
{
"section": "B",
"question_number": "4(iii)(a)",
"answer": "Red colour is used as danger signal because it is scattered least due to its longest wavelength in visible range. Hence, it is visible from a very long distance.",
"marks": 1
},
{
"section": "B",
"question_number": "4(iii)(b)1",
"answer": "Critical angle is 43°",
"marks": 1
},
{
"section": "B",
"question_number": "4(iii)(b)2",
"answer": "Angle of prism = 43°",
"marks": 1
},
{
"section": "B",
"question_number": "4(iii)(b)3",
"answer": "If the blue ray is replaced by indigo or violet, there will be total internal reflection.",
"marks": 1
},
{
"section": "B",
"question_number": "5(i)(a)",
"answer": "8/9",
"marks": 1
},
{
"section": "B",
"question_number": "5(i)(b)",
"answer": "The principle of reversibility",
"marks": 1
},
{
"section": "B",
"question_number": "5(i)(c)",
"answer": "No",
"marks": 1
},
{
"section": "B",
"question_number": "5(ii)(a)",
"answer": "False",
"marks": 1
},
{
"section": "B",
"question_number": "5(ii)(b)",
"answer": "Refractive index = 10t₂/t₁",
"marks": 2
},
{
"section": "B",
"question_number": "5(iii)(a)",
"answer": "[Diagram showing completed ray path]",
"marks": 2
},
{
"section": "B",
"question_number": "5(iii)(b)",
"answer": "1. Angle of incidence\n2. Refractive index",
"marks": 2
},
{
"section": "B",
"question_number": "6(i)(a)",
"answer": "Centre of gravity is the point where the mass of the whole body appears to be concentrated.",
"marks": 1
},
{
"section": "B",
"question_number": "6(i)(b)1",
"answer": "2 cm from base (h/3 = 6/3)",
"marks": 1
},
{
"section": "B",
"question_number": "6(i)(b)2",
"answer": "Yes",
"marks": 1
},
{
"section": "B",
"question_number": "6(ii)(a)",
"answer": "Marble A",
"marks": 1
},
{
"section": "B",
"question_number": "6(ii)(b)",
"answer": "Along both the paths",
"marks": 1
},
{
"section": "B",
"question_number": "6(ii)(c)",
"answer": "Along both the paths",
"marks": 1
},
{
"section": "B",
"question_number": "6(iii)(a)",
"answer": "[Diagram showing tackle system with VR=2]",
"marks": 1
},
{
"section": "B",
"question_number": "6(iii)(b)1",
"answer": "M.A. = 1.6",
"marks": 1
},
{
"section": "B",
"question_number": "6(iii)(b)2",
"answer": "Effort = 30 kgf",
"marks": 2
},
{
"section": "B",
"question_number": "7(i)(a)",
"answer": "Ultrasonic wave",
"marks": 1
},
{
"section": "B",
"question_number": "7(i)(b)",
"answer": "1 s",
"marks": 2
},
{
"section": "B",
"question_number": "7(ii)(a)",
"answer": "²³⁴₉₀Y → ²³⁴₉₁Z + ⁰₋₁e",
"marks": 2
},
{
"section": "B",
"question_number": "7(ii)(b)",
"answer": "U-235",
"marks": 1
},
{
"section": "B",
"question_number": "7(iii)(a)",
"answer": "Resonance",
"marks": 1
},
{
"section": "B",
"question_number": "7(iii)(b)",
"answer": "Natural frequency of the air column matched with the frequency of the tuning fork.",
"marks": 1
},
{
"section": "B",
"question_number": "7(iii)(c)",
"answer": "Length of air column should be decrease. Since frequency is inversely proportional to the air column.",
"marks": 2
},
{
"section": "B",
"question_number": "8(i)(a)",
"answer": "Non-ohmic",
"marks": 1
},
{
"section": "B",
"question_number": "8(i)(b)",
"answer": "The resistance is not constant. It increases as voltage and current increases.",
"marks": 1
},
{
"section": "B",
"question_number": "8(i)(c)",
"answer": "The flow of current through the conductor is directly proportional to the potential difference established across the conductor provide its physical conditions are constant.",
"marks": 2
},
{
"section": "B",
"question_number": "8(ii)(a)",
"answer": "Step down transformer",
"marks": 1
},
{
"section": "B",
"question_number": "8(ii)(b)",
"answer": "Wire of secondary coil is thicker because secondary current is higher than primary current.",
"marks": 1
},
{
"section": "B",
"question_number": "8(iii)(a)",
"answer": "8Ω",
"marks": 1
},
{
"section": "B",
"question_number": "8(iii)(b)",
"answer": "0.5A",
"marks": 1
},
{
"section": "B",
"question_number": "8(iii)(c)",
"answer": "Current in both the resistors are equal because both the arms have same resistance value.",
"marks": 2
},
{
"section": "B",
"question_number": "9(i)",
"answer": "25g",
"marks": 3
},
{
"section": "B",
"question_number": "9(ii)(a)",
"answer": "When lake freezes, it released latent heat to the atmosphere which warms the atmosphere.",
"marks": 1
},
{
"section": "B",
"question_number": "9(ii)(b)",
"answer": "Since there is no change of temperature there is no change in kinetic energy.",
"marks": 1
},
{
"section": "B",
"question_number": "9(ii)(c)",
"answer": "1 g of ice at 0°C has more heat energy than 1 g water at 0°C.",
"marks": 1
},
{
"section": "B",
"question_number": "9(iii)(a)",
"answer": "Number of turns in armature may be increased.",
"marks": 1
},
{
"section": "B",
"question_number": "9(iii)(b)1",
"answer": "Maxwell right hand thumb rule.",
"marks": 1
},
{
"section": "B",
"question_number": "9(iii)(b)2",
"answer": "Direction of current is from X to Y.",
"marks": 1
},
{
"section": "B",
"question_number": "9(iii)(b)3",
"answer": "As R increases, current decreases. So, strength of magnetic field decreases.",
"marks": 1
}
]