Page 1 Nucleus 1. The radius of a nucleus with nucleon number 16 is 3 × 10 –15 m. What would be the radius of other nucleus with nucleon number 128. (A) 6 × 10 –10 m (B) 6 × 10 15 m (C) 6 × 10 –15 m (D) 6 × 10 10 m 2. What is the power output of 92 U 235 reactor if it takes 30 days to use up 2 kg of fuel, and if each fission gives 185 MeV of usable energy ? Avogadro’s number N = 6.02 × 10 26 per kilomole. (A) 18.46 mega watt (B) 28.46 mega watt (C) 38.46 mega watt (D) 58.46 mega watt 3. The activity of a radioactive element decreased to one third of the original activity I 0 in a period of nine years. After a further lapse of nine years its activity will be (A) I 0 (B) (2/3)I 0 (C) I 0 /9 (D) I 0 /6 4. The radioactivity of a sample is R 1 at a time T 1 and R 2 at a time T 2 . If the half – life of the specimen is T, the number of atoms that have disintegrated in the time (T 1 – T 2 ) is proportional to (A) (R 1 T 1 – R 2 T 2 ) (B) (R 1 – R 2 ) (C) (R 1 – R 2 )/T (D) (R 1 – R 2 )T 5. At any instant, the ratio of the amount of radioactive substances is 2 : 1. If their half lives be respectively 12 and 16 hours, then after two days, what will be the ratio amount of the substances ? (A) 1 : 1 (B) 2 : 1 (C) 1 : 2 (D) 1 : 4 6. The half life of radium is 1620 years and its atomic weight is 226. The number of atoms that will decay from its 1gm sample per second will be (A) 3.61 × 10 10 (B) 3.6 × 10 12 (C) 3.1 × 10 15 (D) 31.1 × 10 15 7. A nucleus breaks into two parts whose velocity is in ratio 2 : 1. Find the ratio of their radius. (A) 3 : 2 1/3 (B) 5 : 2 1/3 (C) 1 : 2 1/3 (D) 4 : 3 1/3 8. The activity of a radioactive substance drops to 1/32 of its initial value in 7.5h. Find the half life. (A) 1.5 hours (B) 2.3 hours (C) 3 hours (D) 3.5 hours 9. When the number of nucleons in nuclei increase, the binding energy per nucleon (A) increases continuously with mass number (B) decreases continuously with mass number (C) remains constant with mass number (D) first increases and then decreases with increase of mass number GIITJEE (GURUS FOR IITJEE) SCO 382, Sector 37–D, Chandigarh, Ph. 0172–2628810, 2628811, 4652111 P – 1 Page 2 Nucleus 1. The radius of a nucleus with nucleon number 16 is 3 × 10 –15 m. What would be the radius of other nucleus with nucleon number 128. (A) 6 × 10 –10 m (B) 6 × 10 15 m (C) 6 × 10 –15 m (D) 6 × 10 10 m 2. What is the power output of 92 U 235 reactor if it takes 30 days to use up 2 kg of fuel, and if each fission gives 185 MeV of usable energy ? Avogadro’s number N = 6.02 × 10 26 per kilomole. (A) 18.46 mega watt (B) 28.46 mega watt (C) 38.46 mega watt (D) 58.46 mega watt 3. The activity of a radioactive element decreased to one third of the original activity I 0 in a period of nine years. After a further lapse of nine years its activity will be (A) I 0 (B) (2/3)I 0 (C) I 0 /9 (D) I 0 /6 4. The radioactivity of a sample is R 1 at a time T 1 and R 2 at a time T 2 . If the half – life of the specimen is T, the number of atoms that have disintegrated in the time (T 1 – T 2 ) is proportional to (A) (R 1 T 1 – R 2 T 2 ) (B) (R 1 – R 2 ) (C) (R 1 – R 2 )/T (D) (R 1 – R 2 )T 5. At any instant, the ratio of the amount of radioactive substances is 2 : 1. If their half lives be respectively 12 and 16 hours, then after two days, what will be the ratio amount of the substances ? (A) 1 : 1 (B) 2 : 1 (C) 1 : 2 (D) 1 : 4 6. The half life of radium is 1620 years and its atomic weight is 226. The number of atoms that will decay from its 1gm sample per second will be (A) 3.61 × 10 10 (B) 3.6 × 10 12 (C) 3.1 × 10 15 (D) 31.1 × 10 15 7. A nucleus breaks into two parts whose velocity is in ratio 2 : 1. Find the ratio of their radius. (A) 3 : 2 1/3 (B) 5 : 2 1/3 (C) 1 : 2 1/3 (D) 4 : 3 1/3 8. The activity of a radioactive substance drops to 1/32 of its initial value in 7.5h. Find the half life. (A) 1.5 hours (B) 2.3 hours (C) 3 hours (D) 3.5 hours 9. When the number of nucleons in nuclei increase, the binding energy per nucleon (A) increases continuously with mass number (B) decreases continuously with mass number (C) remains constant with mass number (D) first increases and then decreases with increase of mass number GIITJEE (GURUS FOR IITJEE) SCO 382, Sector 37–D, Chandigarh, Ph. 0172–2628810, 2628811, 4652111 P – 1 10. What is a curie ? (A) Measurement of radioactivity (B) Measurement of temperature (C) Measurement of magnetism (D) Measurement of electric field 11. ?-rays are deflected by (A) an electric field but not by a magnetic field (B) a magnetic field but not by an electric field (C) both electric and magnetic field (D) neither by electric field nor by magnetic field 12. Beta rays emitted by a radioactive material are (A) electromagnetic radiations (B) the electrons orbiting around the nucleus (C) charged particles emitted by nucleus (D) neutral particles 13. The half – life period and the mean life period of a radioactive element are denoted respectively by T h and T m . Then (A) T h = T m (B) T h > T m (C) T h < T m (D) T h = T m 14. Boron rods in a nuclear reactor are used to (A) absorb excess neutrons (B) absorb alpha particle (C) slow down the reaction (D) speed up the reaction 15. Nuclear energy is released in fission since binding energy per nucleon is (A) sometimes larger and sometimes smaller (B) larger for fission fragments than for parent nucleus (C) same for fission fragments and nucleus (D) smaller for fission fragments than for parent nucleus GIITJEE (GURUS FOR IITJEE) SCO 382, Sector 37–D, Chandigarh, Ph. 0172–2628810, 2628811, 4652111 P – 2Read More

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