Atoms and Nuclei (KVPY Stream SB-SX (Class 12 & 1st Year BSC) Physics): Questions 7 - 10 of 14

Get 1 year subscription: Access detailed explanations (illustrated with images and videos) to 268 questions. Access all new questions we will add tracking exam-pattern and syllabus changes. View Sample Explanation or View Features.

Rs. 200.00 or

Question number: 7

» Atoms and Nuclei » Half Life and Mean Life

Appeared in Year: 2014

MCQ▾

Question

The half – life of a particle of mass 1.6 × 10–26 kg is 6.9 s and a stream of such particles is travelling with the kinetic energy of a particle being 0.05 eV. The fraction of particles which will decay when they travel a distance of 1 m is –

Choices

Choice (4) Response

a.

0.1

b.

0.01

c.

0.001

d.

0.0001

Question number: 8

» Atoms and Nuclei » Radioactive Decay Law

MCQ▾

Question

A parent nucleus X is decaying into daughter nucleus Y which in turn decays to Z. The half-lives of X and Y are 6000 years and 30 years respectively. In a certain sample, it is found that the number of Y nuclei hardly change with time. If the number of X nuclei in the sample is 6×1020, the number of Y nuclei present in it is –

Choices

Choice (4) Response

a.

3×1018

b.

6×1020

c.

3×1020

d.

6×1023

Question number: 9

» Atoms and Nuclei » Energy Levels

MCQ▾

Question

The wavelength of the first Balmer line caused by a transition from the n = 4 level to the n = 2 level in hydrogen is λ1. The wavelength of the line caused by an electronic transition from n = 7 to n = 3 is –

Choices

Choice (4) Response

a.

64016λ1

b.

128375λ1

c.

13238λ1

d.

1323640λ1

Question number: 10

» Atoms and Nuclei » Half Life and Mean Life

MCQ▾

Question

A nucleus has a half – life of 45 minutes. At 2: 45 PM its decay rate was measured as 160, 000 counts/sec. What will be the decay rate at 5: 45 PM?

Choices

Choice (4) Response

a.

30, 000countssec

b.

60, 000countssec

c.

10, 000countssec

d.

120, 000countssec

Sign In