{
  "title": "Volume of Sphere - Grade 9 CBSE",
  "total_questions": 100,
  "questions": [
    {"id": 1, "difficulty": "easy", "question": "What is formula for volume of sphere?", "options": {"A": "4/3 πr²", "B": "4/3 πr³", "C": "4πr²", "D": "2/3 πr³"}, "correct_answer": "B"},
    {"id": 2, "difficulty": "easy", "question": "Volume of sphere with radius 7 cm:", "options": {"A": "1372/3 π cm³", "B": "343π cm³", "C": "686/3 π cm³", "D": "1437/3 π cm³"}, "correct_answer": "A"},
    {"id": 3, "difficulty": "easy", "question": "If radius=14 cm, volume=", "options": {"A": "10976/3 π cm³", "B": "5488/3 π cm³", "C": "2744π cm³", "D": "1372π cm³"}, "correct_answer": "A"},
    {"id": 4, "difficulty": "easy", "question": "Sphere: r=3.5 cm. Volume:", "options": {"A": "42.875/3 π cm³", "B": "85.75/3 π cm³", "C": "171.5/3 π cm³", "D": "343/3 π cm³"}, "correct_answer": "C"},
    {"id": 5, "difficulty": "easy", "question": "Volume of sphere diameter 14 cm:", "options": {"A": "1372/3 π cm³", "B": "686/3 π cm³", "C": "343/3 π cm³", "D": "171.5/3 π cm³"}, "correct_answer": "A"},
    {"id": 6, "difficulty": "easy", "question": "If volume=38808/7 cm³, find r (π=22/7).", "options": {"A": "10.5 cm", "B": "11 cm", "C": "11.5 cm", "D": "12 cm"}, "correct_answer": "A"},
    {"id": 7, "difficulty": "easy", "question": "Sphere: r=10 cm. Volume:", "options": {"A": "1000π cm³", "B": "2000/3 π cm³", "C": "4000/3 π cm³", "D": "8000/3 π cm³"}, "correct_answer": "C"},
    {"id": 8, "difficulty": "easy", "question": "Volume of sphere diameter 20 cm:", "options": {"A": "1000/3 π cm³", "B": "2000/3 π cm³", "C": "4000/3 π cm³", "D": "8000/3 π cm³"}, "correct_answer": "C"},
    {"id": 9, "difficulty": "easy", "question": "If volume=179.67 cm³ (π=3.14), find r.", "options": {"A": "3 cm", "B": "3.5 cm", "C": "4 cm", "D": "4.5 cm"}, "correct_answer": "B"},
    {"id": 10, "difficulty": "easy", "question": "Sphere: r=4.2 cm. Volume:", "options": {"A": "74.088π cm³", "B": "98.784π cm³", "C": "123.48π cm³", "D": "148.176π cm³"}, "correct_answer": "A"},
    {"id": 11, "difficulty": "easy", "question": "Volume of sphere r=5 cm:", "options": {"A": "125π cm³", "B": "250/3 π cm³", "C": "500/3 π cm³", "D": "1000/3 π cm³"}, "correct_answer": "C"},
    {"id": 12, "difficulty": "easy", "question": "If volume=113.04 cm³ (π=3.14), find r.", "options": {"A": "2 cm", "B": "2.5 cm", "C": "3 cm", "D": "3.5 cm"}, "correct_answer": "C"},
    {"id": 13, "difficulty": "easy", "question": "Sphere: diameter 28 cm. Volume:", "options": {"A": "10976/3 π cm³", "B": "21952/3 π cm³", "C": "43904/3 π cm³", "D": "87808/3 π cm³"}, "correct_answer": "A"},
    {"id": 14, "difficulty": "easy", "question": "Volume of sphere r=6 cm:", "options": {"A": "72π cm³", "B": "144π cm³", "C": "216π cm³", "D": "288π cm³"}, "correct_answer": "D"},
    {"id": 15, "difficulty": "easy", "question": "If volume=523.33 cm³ (π=3.14), find r.", "options": {"A": "4 cm", "B": "4.5 cm", "C": "5 cm", "D": "5.5 cm"}, "correct_answer": "C"},
    {"id": 16, "difficulty": "easy", "question": "Sphere: r=8.4 cm. Volume:", "options": {"A": "592.704π cm³", "B": "790.272π cm³", "C": "987.84π cm³", "D": "1185.408π cm³"}, "correct_answer": "A"},
    {"id": 17, "difficulty": "easy", "question": "Volume of sphere diameter 42 cm:", "options": {"A": "37044/3 π cm³", "B": "74088/3 π cm³", "C": "148176/3 π cm³", "D": "296352/3 π cm³"}, "correct_answer": "A"},
    {"id": 18, "difficulty": "easy", "question": "If volume=904.32 cm³ (π=3.14), find r.", "options": {"A": "5 cm", "B": "5.5 cm", "C": "6 cm", "D": "6.5 cm"}, "correct_answer": "C"},
    {"id": 19, "difficulty": "easy", "question": "Sphere: r=9.1 cm. Volume:", "options": {"A": "753.571/3 π cm³", "B": "1507.142/3 π cm³", "C": "2260.713/3 π cm³", "D": "3014.284/3 π cm³"}, "correct_answer": "A"},
    {"id": 20, "difficulty": "easy", "question": "Volume of sphere r=10.5 cm:", "options": {"A": "1157.625π cm³", "B": "1543.5π cm³", "C": "2315.25π cm³", "D": "4630.5π cm³"}, "correct_answer": "A"},

    {"id": 21, "difficulty": "medium", "question": "Sphere has volume 38808 cm³. Find radius (π=22/7).", "options": {"A": "19 cm", "B": "20 cm", "C": "21 cm", "D": "22 cm"}, "correct_answer": "C"},
    {"id": 22, "difficulty": "medium", "question": "Volume of sphere is 11498.67 cm³ (π=3.14). Find radius.", "options": {"A": "12 cm", "B": "13 cm", "C": "14 cm", "D": "15 cm"}, "correct_answer": "C"},
    {"id": 23, "difficulty": "medium", "question": "Sphere: r=8.75 cm. Volume:", "options": {"A": "669.921875/3 π cm³", "B": "1339.84375/3 π cm³", "C": "2679.6875/3 π cm³", "D": "5359.375/3 π cm³"}, "correct_answer": "A"},
    {"id": 24, "difficulty": "medium", "question": "If volume of sphere is 179.5 cm³ (π=3.14), find diameter.", "options": {"A": "6 cm", "B": "6.5 cm", "C": "7 cm", "D": "7.5 cm"}, "correct_answer": "C"},
    {"id": 25, "difficulty": "medium", "question": "Sphere has volume 5572.45 cm³ (π=3.14). Find radius.", "options": {"A": "10 cm", "B": "10.5 cm", "C": "11 cm", "D": "11.5 cm"}, "correct_answer": "C"},
    {"id": 26, "difficulty": "medium", "question": "Volume of sphere is 2145.52 cm³ (π=3.14). Find radius.", "options": {"A": "7.5 cm", "B": "8 cm", "C": "8.5 cm", "D": "9 cm"}, "correct_answer": "B"},
    {"id": 27, "difficulty": "medium", "question": "Sphere: r=12.6 cm. Volume:", "options": {"A": "2000.376π cm³", "B": "2667.168π cm³", "C": "4000.752π cm³", "D": "8001.504π cm³"}, "correct_answer": "A"},
    {"id": 28, "difficulty": "medium", "question": "If volume is 3052.08 cm³ (π=3.14), find diameter.", "options": {"A": "16 cm", "B": "17 cm", "C": "18 cm", "D": "19 cm"}, "correct_answer": "C"},
    {"id": 29, "difficulty": "medium", "question": "Sphere has volume 4188.79 cm³ (π=3.14). Find radius.", "options": {"A": "9.5 cm", "B": "10 cm", "C": "10.5 cm", "D": "11 cm"}, "correct_answer": "B"},
    {"id": 30, "difficulty": "medium", "question": "Volume of sphere diameter 35 cm:", "options": {"A": "10718.75/3 π cm³", "B": "21437.5/3 π cm³", "C": "42875/3 π cm³", "D": "85750/3 π cm³"}, "correct_answer": "B"},
    {"id": 31, "difficulty": "medium", "question": "Sphere: r=15.75 cm. Volume:", "options": {"A": "3906.984375/3 π cm³", "B": "7813.96875/3 π cm³", "C": "15627.9375/3 π cm³", "D": "31255.875/3 π cm³"}, "correct_answer": "A"},
    {"id": 32, "difficulty": "medium", "question": "If volume is 5575.28 cm³ (π=3.14), find radius.", "options": {"A": "10.5 cm", "B": "11 cm", "C": "11.5 cm", "D": "12 cm"}, "correct_answer": "B"},
    {"id": 33, "difficulty": "medium", "question": "Sphere has volume 7238.23 cm³ (π=3.14). Find diameter.", "options": {"A": "22 cm", "B": "23 cm", "C": "24 cm", "D": "25 cm"}, "correct_answer": "C"},
    {"id": 34, "difficulty": "medium", "question": "Volume of sphere r=16.8 cm:", "options": {"A": "4741.632π cm³", "B": "6322.176π cm³", "C": "9483.264π cm³", "D": "18966.528π cm³"}, "correct_answer": "A"},
    {"id": 35, "difficulty": "medium", "question": "If volume is 9047.79 cm³ (π=3.14), find radius.", "options": {"A": "12 cm", "B": "12.5 cm", "C": "13 cm", "D": "13.5 cm"}, "correct_answer": "C"},
    {"id": 36, "difficulty": "medium", "question": "Sphere: diameter 56 cm. Volume:", "options": {"A": "175616/3 π cm³", "B": "351232/3 π cm³", "C": "702464/3 π cm³", "D": "1404928/3 π cm³"}, "correct_answer": "A"},
    {"id": 37, "difficulty": "medium", "question": "Volume of sphere r=18.9 cm:", "options": {"A": "6751.269π cm³", "B": "9001.692π cm³", "C": "13502.538π cm³", "D": "27005.076π cm³"}, "correct_answer": "A"},
    {"id": 38, "difficulty": "medium", "question": "If volume is 11494.04 cm³ (π=3.14), find diameter.", "options": {"A": "26 cm", "B": "27 cm", "C": "28 cm", "D": "29 cm"}, "correct_answer": "C"},
    {"id": 39, "difficulty": "medium", "question": "Sphere has volume 14137.17 cm³ (π=3.14). Find radius.", "options": {"A": "14 cm", "B": "14.5 cm", "C": "15 cm", "D": "15.5 cm"}, "correct_answer": "C"},
    {"id": 40, "difficulty": "medium", "question": "Volume of sphere diameter 70 cm:", "options": {"A": "85750/3 π cm³", "B": "171500/3 π cm³", "C": "343000/3 π cm³", "D": "686000/3 π cm³"}, "correct_answer": "B"},
    {"id": 41, "difficulty": "medium", "question": "Sphere: r=21.7 cm. Volume:", "options": {"A": "10218.313/3 π cm³", "B": "20436.626/3 π cm³", "C": "40873.252/3 π cm³", "D": "81746.504/3 π cm³"}, "correct_answer": "A"},
    {"id": 42, "difficulty": "medium", "question": "If volume is 17959.5 cm³ (π=3.14), find radius.", "options": {"A": "15.5 cm", "B": "16 cm", "C": "16.5 cm", "D": "17 cm"}, "correct_answer": "C"},
    {"id": 43, "difficulty": "medium", "question": "Sphere has volume 21488.22 cm³ (π=3.14). Find diameter.", "options": {"A": "32 cm", "B": "33 cm", "C": "34 cm", "D": "35 cm"}, "correct_answer": "C"},
    {"id": 44, "difficulty": "medium", "question": "Volume of sphere r=24.5 cm:", "options": {"A": "14706.125π cm³", "B": "19608.167π cm³", "C": "29412.25π cm³", "D": "58824.5π cm³"}, "correct_answer": "A"},
    {"id": 45, "difficulty": "medium", "question": "If volume is 26794.67 cm³ (π=3.14), find radius.", "options": {"A": "17 cm", "B": "17.5 cm", "C": "18 cm", "D": "18.5 cm"}, "correct_answer": "C"},
    {"id": 46, "difficulty": "medium", "question": "Sphere: diameter 84 cm. Volume:", "options": {"A": "296352/3 π cm³", "B": "592704/3 π cm³", "C": "1185408/3 π cm³", "D": "2370816/3 π cm³"}, "correct_answer": "A"},
    {"id": 47, "difficulty": "medium", "question": "Volume of sphere r=27.3 cm:", "options": {"A": "20346.417/3 π cm³", "B": "40692.834/3 π cm³", "C": "81385.668/3 π cm³", "D": "162771.336/3 π cm³"}, "correct_answer": "A"},
    {"id": 48, "difficulty": "medium", "question": "If volume is 33510.32 cm³ (π=3.14), find diameter.", "options": {"A": "38 cm", "B": "39 cm", "C": "40 cm", "D": "41 cm"}, "correct_answer": "C"},
    {"id": 49, "difficulty": "medium", "question": "Sphere has volume 41887.9 cm³ (π=3.14). Find radius.", "options": {"A": "20 cm", "B": "20.5 cm", "C": "21 cm", "D": "21.5 cm"}, "correct_answer": "C"},
    {"id": 50, "difficulty": "medium", "question": "Volume of sphere diameter 98 cm:", "options": {"A": "235298/3 π cm³", "B": "470596/3 π cm³", "C": "941192/3 π cm³", "D": "1882384/3 π cm³"}, "correct_answer": "A"},
    {"id": 51, "difficulty": "medium", "question": "Sphere: r=30.8 cm. Volume:", "options": {"A": "29218.112π cm³", "B": "38957.483π cm³", "C": "58436.224π cm³", "D": "116872.448π cm³"}, "correct_answer": "A"},
    {"id": 52, "difficulty": "medium", "question": "If volume is 52359.47 cm³ (π=3.14), find radius.", "options": {"A": "22 cm", "B": "22.5 cm", "C": "23 cm", "D": "23.5 cm"}, "correct_answer": "C"},
    {"id": 53, "difficulty": "medium", "question": "Sphere has volume 65449.85 cm³ (π=3.14). Find diameter.", "options": {"A": "46 cm", "B": "47 cm", "C": "48 cm", "D": "49 cm"}, "correct_answer": "B"},
    {"id": 54, "difficulty": "medium", "question": "Volume of sphere r=34.3 cm:", "options": {"A": "40353.607/3 π cm³", "B": "80707.214/3 π cm³", "C": "161414.428/3 π cm³", "D": "322828.856/3 π cm³"}, "correct_answer": "A"},
    {"id": 55, "difficulty": "medium", "question": "If volume is 82467.9 cm³ (π=3.14), find radius.", "options": {"A": "26 cm", "B": "26.5 cm", "C": "27 cm", "D": "27.5 cm"}, "correct_answer": "C"},
    {"id": 56, "difficulty": "medium", "question": "Sphere: diameter 112 cm. Volume:", "options": {"A": "702464/3 π cm³", "B": "1404928/3 π cm³", "C": "2809856/3 π cm³", "D": "5619712/3 π cm³"}, "correct_answer": "A"},
    {"id": 57, "difficulty": "medium", "question": "Volume of sphere r=38.5 cm:", "options": {"A": "571.7875π cm³", "B": "22871.5π cm³", "C": "45743π cm³", "D": "91486π cm³"}, "correct_answer": "B"},
    {"id": 58, "difficulty": "medium", "question": "If volume is 107232.6 cm³ (π=3.14), find diameter.", "options": {"A": "54 cm", "B": "55 cm", "C": "56 cm", "D": "57 cm"}, "correct_answer": "C"},
    {"id": 59, "difficulty": "medium", "question": "Sphere has volume 134092.9 cm³ (π=3.14). Find radius.", "options": {"A": "31 cm", "B": "31.5 cm", "C": "32 cm", "D": "32.5 cm"}, "correct_answer": "C"},
    {"id": 60, "difficulty": "medium", "question": "Volume of sphere diameter 126 cm:", "options": {"A": "1000188/3 π cm³", "B": "2000376/3 π cm³", "C": "4000752/3 π cm³", "D": "8001504/3 π cm³"}, "correct_answer": "A"},
    {"id": 61, "difficulty": "medium", "question": "Sphere: r=43.4 cm. Volume:", "options": {"A": "81739.304/3 π cm³", "B": "163478.608/3 π cm³", "C": "326957.216/3 π cm³", "D": "653914.432/3 π cm³"}, "correct_answer": "A"},
    {"id": 62, "difficulty": "medium", "question": "If volume is 164636.2 cm³ (π=3.14), find radius.", "options": {"A": "34 cm", "B": "34.5 cm", "C": "35 cm", "D": "35.5 cm"}, "correct_answer": "B"},
    {"id": 63, "difficulty": "medium", "question": "Sphere has volume 205795.2 cm³ (π=3.14). Find diameter.", "options": {"A": "72 cm", "B": "73 cm", "C": "74 cm", "D": "75 cm"}, "correct_answer": "C"},
    {"id": 64, "difficulty": "medium", "question": "Volume of sphere r=48.3 cm:", "options": {"A": "112678.587/3 π cm³", "B": "225357.174/3 π cm³", "C": "450714.348/3 π cm³", "D": "901428.696/3 π cm³"}, "correct_answer": "A"},
    {"id": 65, "difficulty": "medium", "question": "If volume is 251327.4 cm³ (π=3.14), find radius.", "options": {"A": "39 cm", "B": "39.5 cm", "C": "40 cm", "D": "40.5 cm"}, "correct_answer": "B"},
    {"id": 66, "difficulty": "medium", "question": "Sphere: diameter 140 cm. Volume:", "options": {"A": "1372000/3 π cm³", "B": "2744000/3 π cm³", "C": "5488000/3 π cm³", "D": "10976000/3 π cm³"}, "correct_answer": "A"},
    {"id": 67, "difficulty": "medium", "question": "Volume of sphere r=53.9 cm:", "options": {"A": "156590.819/3 π cm³", "B": "313181.638/3 π cm³", "C": "626363.276/3 π cm³", "D": "1252726.552/3 π cm³"}, "correct_answer": "A"},
    {"id": 68, "difficulty": "medium", "question": "If volume is 305363.5 cm³ (π=3.14), find diameter.", "options": {"A": "88 cm", "B": "89 cm", "C": "90 cm", "D": "91 cm"}, "correct_answer": "C"},
    {"id": 69, "difficulty": "medium", "question": "Sphere has volume 381703.5 cm³ (π=3.14). Find radius.", "options": {"A": "45 cm", "B": "45.5 cm", "C": "46 cm", "D": "46.5 cm"}, "correct_answer": "B"},
    {"id": 70, "difficulty": "medium", "question": "Volume of sphere diameter 154 cm:", "options": {"A": "1826136/3 π cm³", "B": "3652272/3 π cm³", "C": "7304544/3 π cm³", "D": "14609088/3 π cm³"}, "correct_answer": "A"},
    {"id": 71, "difficulty": "medium", "question": "Sphere: r=60.2 cm. Volume:", "options": {"A": "218167.208/3 π cm³", "B": "436334.416/3 π cm³", "C": "872668.832/3 π cm³", "D": "1745337.664/3 π cm³"}, "correct_answer": "A"},
    {"id": 72, "difficulty": "medium", "question": "If volume is 465564.5 cm³ (π=3.14), find radius.", "options": {"A": "48 cm", "B": "48.5 cm", "C": "49 cm", "D": "49.5 cm"}, "correct_answer": "B"},
    {"id": 73, "difficulty": "medium", "question": "Sphere has volume 581955.6 cm³ (π=3.14). Find diameter.", "options": {"A": "104 cm", "B": "105 cm", "C": "106 cm", "D": "107 cm"}, "correct_answer": "C"},
    {"id": 74, "difficulty": "medium", "question": "Volume of sphere r=67.9 cm:", "options": {"A": "312900.739/3 π cm³", "B": "625801.478/3 π cm³", "C": "1251602.956/3 π cm³", "D": "2503205.912/3 π cm³"}, "correct_answer": "A"},
    {"id": 75, "difficulty": "medium", "question": "If volume is 728476.6 cm³ (π=3.14), find radius.", "options": {"A": "56 cm", "B": "56.5 cm", "C": "57 cm", "D": "57.5 cm"}, "correct_answer": "B"},
    {"id": 76, "difficulty": "medium", "question": "Sphere: diameter 168 cm. Volume:", "options": {"A": "2963520/3 π cm³", "B": "5927040/3 π cm³", "C": "11854080/3 π cm³", "D": "23708160/3 π cm³"}, "correct_answer": "A"},
    {"id": 77, "difficulty": "medium", "question": "Volume of sphere r=76.3 cm:", "options": {"A": "444194.047/3 π cm³", "B": "888388.094/3 π cm³", "C": "1776776.188/3 π cm³", "D": "3553552.376/3 π cm³"}, "correct_answer": "A"},
    {"id": 78, "difficulty": "medium", "question": "If volume is 904778.7 cm³ (π=3.14), find diameter.", "options": {"A": "120 cm", "B": "121 cm", "C": "122 cm", "D": "123 cm"}, "correct_answer": "C"},
    {"id": 79, "difficulty": "medium", "question": "Sphere has volume 1130973.4 cm³ (π=3.14). Find radius.", "options": {"A": "65 cm", "B": "65.5 cm", "C": "66 cm", "D": "66.5 cm"}, "correct_answer": "B"},
    {"id": 80, "difficulty": "medium", "question": "Volume of sphere diameter 182 cm:", "options": {"A": "3013276/3 π cm³", "B": "6026552/3 π cm³", "C": "12053104/3 π cm³", "D": "24106208/3 π cm³"}, "correct_answer": "A"},

    {"id": 81, "difficulty": "hard", "question": "Sphere melted to form cylinder of radius 7 cm and height 14 cm. Find radius of sphere.", "options": {"A": "7 cm", "B": "7√2 cm", "C": "7∛2 cm", "D": "14/∛2 cm"}, "correct_answer": "C"},
    {"id": 82, "difficulty": "hard", "question": "Two spheres have volumes in ratio 64:125. Find ratio of surface areas.", "options": {"A": "4:5", "B": "8:10", "C": "16:25", "D": "64:125"}, "correct_answer": "C"},
    {"id": 83, "difficulty": "hard", "question": "If radius of sphere increased by 20%, find % increase in volume.", "options": {"A": "44%", "B": "72.8%", "C": "80%", "D": "82.8%"}, "correct_answer": "B"},
    {"id": 84, "difficulty": "hard", "question": "Sphere has same volume as cylinder of radius 6 cm and height 6 cm. Find radius of sphere.", "options": {"A": "3√6 cm", "B": "6 cm", "C": "6√2 cm", "D": "9 cm"}, "correct_answer": "A"},
    {"id": 85, "difficulty": "hard", "question": "Eight spheres of radius 7 cm melted to form one sphere. Find radius of new sphere.", "options": {"A": "14 cm", "B": "21 cm", "C": "28 cm", "D": "35 cm"}, "correct_answer": "A"},
    {"id": 86, "difficulty": "hard", "question": "If volume of sphere is 38808 cm³, find surface area (π=22/7).", "options": {"A": "2464 cm²", "B": "2772 cm²", "C": "3696 cm²", "D": "5544 cm²"}, "correct_answer": "D"},
    {"id": 87, "difficulty": "hard", "question": "Sphere radius halved. What % of original volume is new volume?", "options": {"A": "12.5%", "B": "25%", "C": "50%", "D": "75%"}, "correct_answer": "A"},
    {"id": 88, "difficulty": "hard", "question": "Hollow sphere has outer radius 14 cm, inner radius 7 cm. Find volume of metal.", "options": {"A": "2156π cm³", "B": "4312π cm³", "C": "6468π cm³", "D": "8624π cm³"}, "correct_answer": "B"},
    {"id": 89, "difficulty": "hard", "question": "Two spheres have radii ratio 2:3. Find ratio of volumes.", "options": {"A": "4:9", "B": "8:27", "C": "16:81", "D": "32:243"}, "correct_answer": "B"},
    {"id": 90, "difficulty": "hard", "question": "Sphere of radius 10.5 cm melted to form cones of radius 3.5 cm, height 7 cm. How many cones?", "options": {"A": "12", "B": "18", "C": "24", "D": "36"}, "correct_answer": "B"},
    {"id": 91, "difficulty": "hard", "question": "If diameter of sphere increased by 50%, volume increases by:", "options": {"A": "50%", "B": "125%", "C": "237.5%", "D": "337.5%"}, "correct_answer": "C"},
    {"id": 92, "difficulty": "hard", "question": "Sphere has volume 179.67 cm³. Find curved surface area (π=3.14).", "options": {"A": "113.04 cm²", "B": "153.86 cm²", "C": "314 cm²", "D": "452.16 cm²"}, "correct_answer": "B"},
    {"id": 93, "difficulty": "hard", "question": "Water in spherical bowl radius 21 cm poured into cylinder radius 14 cm. Find height of water.", "options": {"A": "28 cm", "B": "31.5 cm", "C": "42 cm", "D": "63 cm"}, "correct_answer": "B"},
    {"id": 94, "difficulty": "hard", "question": "Sphere volume is 4/3 times cone volume. Both have same radius. Find ratio of heights (sphere:cone).", "options": {"A": "1:1", "B": "1:2", "C": "1:3", "D": "1:4"}, "correct_answer": "D"},
    {"id": 95, "difficulty": "hard", "question": "If surface area of sphere 616 cm², find volume (π=22/7).", "options": {"A": "1437.33 cm³", "B": "1796.67 cm³", "C": "2156 cm³", "D": "2874.67 cm³"}, "correct_answer": "A"},
    {"id": 96, "difficulty": "hard", "question": "Sphere of radius 5 cm melted to form wire of diameter 0.5 cm. Find length of wire.", "options": {"A": "266.67 cm", "B": "533.33 cm", "C": "800 cm", "D": "1600 cm"}, "correct_answer": "D"},
    {"id": 97, "difficulty": "hard", "question": "If volume of sphere increased by 72.8%, find % increase in radius.", "options": {"A": "10%", "B": "15%", "C": "20%", "D": "25%"}, "correct_answer": "C"},
    {"id": 98, "difficulty": "hard", "question": "Hollow sphere thickness 1 cm has outer diameter 20 cm. Find volume of material.", "options": {"A": "636.67π cm³", "B": "1273.33π cm³", "C": "1909.33π cm³", "D": "2545.33π cm³"}, "correct_answer": "B"},
    {"id": 99, "difficulty": "hard", "question": "Sphere fits exactly in cube. If sphere volume 288π cm³, find cube side.", "options": {"A": "6 cm", "B": "8 cm", "C": "10 cm", "D": "12 cm"}, "correct_answer": "D"},
    {"id": 100, "difficulty": "hard", "question": "Two spheres have volumes 8π cm³ and 27π cm³. Find ratio of surface areas.", "options": {"A": "2:3", "B": "4:9", "C": "8:27", "D": "16:81"}, "correct_answer": "B"}
  ]
}