13. NUCLEI( Objective Question Answer 2022 )

1. How many electrons are contained in ^238₉₂U nucleus ?

(A) 92
(B) 146
(C) 238
(D) O

2. Chadwick was awarded the Nobel prize in Physics in 1935 for his discovery of :

(A) electron
(B) proton
(C) neutron
(D) None of these

3. The density of a nucleus is of the order of:

(A) 1015 kg m^-3
(B) 1018 kg m^-3
(C) 1017 kg m^-3
(D) 1016 kg m^-3

4. In the given reaction :

radioactive radiations are emitted in the sequence

(A) ∝, β, ϒ
(B) β, ∝, ϒ
(C) ϒ, ∝, β
(D) β, ϒ, ∝

5. When the mass of a sample of a radioactive substance decreases, the mean life of the sample :

(A) increases
(B) decreases
(C) remain unchanged
(D) first decreases then increases

6. The order of nuclear density is :

(A) 10³
(B) 10¹⁷
(C) 10⁶
(D) None

7. The isotope generally used for the treatment of cancer is :

(A) I¹³¹
(B) Hg¹⁹⁷
(C) O¹⁵
(D) Co⁶⁰

8. What percentage of radioactive substance is left after 5 half lives ?

(A) 3.125 %
(B) 6.25 %
(C) 12.33 %
(D) 31 %

9. Mass is converted into energy according to the relation:

(A) E = me2
(B) E = mgh
(C) E = 1/2me²
(D) E = mgH/C²

10. The helium atom does not contain :

(A) two protons
(B) two electrons
(C) two neutrons
(D) six nucleons

11. The more readily fissionable isotope of uranium has an atomic mass of :

(A) 234
(B) 235
(C) 236
(D) 238

12. Energy of electron in the 1st orbit of H-atom is :

(A) -13.6 MeV
(B) –13.6 eV
(C) –13.6 J
(D) 13.6 J

13. The mass no. of a nucleus is M and its atomic no. is z. The number of neutrons in the nucleus is :

(A) M – Z
(B) M
(C) Z
(D) M + Z

14. The phenomena of radioactivity is :

(A) Exothermic change with increase or decrease with temperature
(B) increases on applied pressure
(C) nuclear process does not depend on external factors
(D) None of these

15. What percentage of original radioactive atom is left after four half life ?

(A) 6%
(B) 10%
(C) 20%
(D) 25%

Class 12th physics objective question in English