JEE Physics Nuclei MCQs Set B

Question. In proton-proton cycle, four hydrogen atoms combine to release energy
(a) 26.7 MeV
(b) 26.7 KeV
(c) 2.67 KeV
(d) 2.67 MeV

Answer: A

Question. 37 Rutherford equals
(a) 1 milli bacquerel
(b) 1 milli curie
(c) 1 micro bacquerel
(d) 1 micro curie

Answer: A

Question. Which of these is incorrect about nuclear forces?
(a) Hadrons do not experience strong nuclear force
(b) Nuclear force is not a central force
(c) Nuclear forces are derived from quark-quark interaction
(d) They are independent of charge

Answer: A

Question. The volume occupied by an atom is greater than the volume of the nucleus by a factor of about
(a) 10¹⁵
(b) 10¹⁴
(c) 10¹⁰
(d) 10¹²

Answer: A

Question. Alpha particles are
(a) Ionized helium atoms
(b) Protons
(c) Positron
(d) Neutrally charged

Answer: A

Question. Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be
(a) 1 : 1
(b) 1 : 3
(c) 3 : 1
(d) (3)^1/3 : 1

Answer: A

Question. The mass number of a nucleus is
(a) Sometimes less than and sometimes more than its atomic number
(b) Sometimes equal to its atomic number
(c) Always more than its atomic number
(d) Always less than its atomic number

Answer: A

Question. A nucleus ruptures into two nuclear parts, which have their velocity ratio equal to 2 : 1. What will be the ratio of their nuclear size (nuclear radius)?
(a) 1 : 2^1/3
(b) 2^1/3 : 1
(c) 1 : 3^1/2
(d) 3^1/2 : 1

Answer: A

Question. Half-lives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the samples of A and B have equal number of nuclei. After 80 minutes the ratio of remaining numbers of A and B nuclei is
(a) 1 : 4
(b) 4 : 1
(c) 1 : 16
(d) 1 : 1

Answer: A

Question. Nuclear-Fission is best explained by
(a) Liquid drop model
(b) Independent particle model of the nucleus
(c) Proton-proton cycle
(d) None of these

Answer: A

Question. Half life of a radioactive element is 12.5 hour and its quantity is 256 gm. After how much time its quantity will remain 1 g?
(a) 100 hrs
(b) 150 hrs
(c) 200 hrs
(d) 50 hrs

Answer: A

Question. Energy released in nuclear fission is due to
(a) Total binding energy of fragments is more than the binding energy of parental element
(b) Some mass is converted into charge
(c) Total binding energy of fragments is less than the binding energy of parental element
(d) Total binding energy of fragments is equals to the binding energy of parental element

Answer: A

Question. Fission of nuclei is possible because the binding energy per nucleon in them
(a) Decreases with mass number at high mass numbers
(b) Increases with mass number at high mass numbers
(c) Decreases with mass number at low mass numbers
(d) Increases with mass number at low mass numbers

Answer: A

Question. The half life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after
(a) 3200 years
(b) 2400 years
(c) 6400 years
(d) 4800 years

Answer: A

Question. A sample of radioactive element has a mass of 10 g at an instant t = 0. The approximate mass of this element in the sample after two mean lives is
(a) 1.35 g
(b) 2.50 g
(c) 3.70 g
(d) 6.30 g

Answer: A

Question. A sample of radioactive element contains 4 x 10¹⁶ active nuclei. Half life of element is 10 days, then number of decayed nuclei after 30 days
(a) 3.5 × 10¹⁶
(b) 3 × 10¹⁶
(c) 1 × 10¹⁶
(d) None of these

Answer: A

Question. The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an
(a) Isotope of parent
(b) Isobar of parent
(c) Isomer of parent
(d) Isotone of parent

Answer: A

Question. Q value of a nuclear reaction is positive. The reaction is
(a) Exothermic
(b) Elastic
(c) Endothermic
(d) Both exothermic and endothermic

Answer: A

Question. A mixture consists of two radioactive materials A₁ and A₂ with half lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A₁ and 160 g of A₂. The amount of the two in the mixture will become equal after
(a) 40 s
(b) 20 s
(c) 60 s
(d) 80 s

Answer: A

Question. The half life of a radioactive isotope X is 50 years. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of the rock was estimated to be
(a) 200 years
(b) 250 years
(c) 150 years
(d) 100 years

Answer: A

Question. Fusion reaction takes place at high temperature because
(a) Kinetic energy is high enough to overcome the coulomb repulsion between nuclei
(b) Atoms get ionised at high temperature
(c) Nuclei break up at high temperature
(d) Molecules break up at high temperature

Answer: A

Question. When two nuclei (with A = 8) join to form a heavier nucleus, the binding energy (B.E.) per nucleon of the heavier nuclei is
(a) More than the B.E. per nucleon of the lighter nuclei
(b) Same as the B.E. per nucleon of the lighter nuclei
(c) Less than the B.E. per nucleon of the lighter nuclei
(d) Double the B.E. per nucleon of the lighter nuclei

Answer: A

Question. When helium nuclei bombard beryllium nuclei, then
(a) Neutrons are emitted
(b) Electrons are emitted
(c) Protons are emitted
(d) Protons and neutrons are emitted

Answer: A

Question. A radioactive substance has 10⁸ nuclei. Its half life is 30 s. The number of nuclei left after 15 s is nearly
(a) 3 × 10⁶
(b) 7 × 10⁷
(c) 5 × 10⁸
(d) 2 × 10⁵

Answer: A

Question. In a nuclear reaction transforming a nucleus into another with the emission of a positron, the neutron proton ratio
(a) Increases
(b) May decrease or increase
(c) Decreases
(d) Remains same

Answer: A

Question. Which of the following is used as a moderator in nuclear reactor?
(a) Heavy water
(b) Uranium
(c) Plutonium
(d) Cadmium

Answer: A

Question. Which of the following are suitable for the fusion process?
(a) Light nuclei
(b) Heavy nuclei
(c) Element must be lying in the middle of the periodic table
(d) Middle elements, which are lying on binding energy curve

Answer: A

Question. Solar energy is mainly caused due to
(a) Fusion of protons during synthesis of heavier elements
(b) Gravitational contraction
(c) Fission of uranium present in the Sun
(d) Burning of hydrogen in the oxygen

Answer: A