Atoms and Nuclei (KVPY Stream-SA (Class 11) Physics): Questions 9 - 14 of 15

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Question number: 9

» Atoms and Nuclei » Radioactivity

Appeared in Year: 2015

MCQ▾

Question

The beta particles of a radioactive metal originate from

Choices

Choice (4) Response

a.

The free electrons in the metal

b.

The orbiting electrons of the metal atoms

c.

The photons released from the nucleus

d.

The nucleus of the metal atoms

Question number: 10

» Atoms and Nuclei » Composition and Size of Nucleus

MCQ▾

Question

A nucleus of bismuth 83209Bi emits three electrons followed by two alpha particles. The resulting nucleus will have –

Choices

Choice (4) Response

a.

78 protons and 134 neutrons

b.

82 protons and 92 neutrons

c.

82 protons and 128 neutrons

d.

80 protons and 119 neutrons

Question number: 11

» Atoms and Nuclei » Radioactivity

MCQ▾

Question

The activity of a radioactive sample reduces to 15 of its original value in 9 hours. What will be its activity in 27 hours?

Choices

Choice (4) Response

a.

1125

b.

17

c.

1124

d.

121

Question number: 12

» Atoms and Nuclei » Radioactivity

MCQ▾

Question

92U238 atom disintegrates to 89Ac226 with a half-life of 4.7 ⨯ 109 years by emitting three alpha and n beta particles. Here n is –

Choices

Choice (4) Response

a.

2

b.

3

c.

4

d.

5

Question number: 13

» Atoms and Nuclei » Radioactivity

MCQ▾

Question

The activity of a radioactive sample reduces to 13 of its original value in 2 hours. What will be its activity in 6 hours?

Choices

Choice (4) Response

a.

13

b.

127

c.

181

d.

19

Question number: 14

» Atoms and Nuclei » Isotopes

MCQ▾

Question

The isotopes 238U and 235U occur in nature in the ratio 150: 1. Assuming that at the time of earth formation they were present in equal amount; make an estimation of the age of the earth. The half-lives of 238U and 235U are 5.7×109yr and 6.3×108yr respectively.

[log10150=2.1761&log102=0.3010]

Choices

Choice (4) Response

a.

5.12×108years

b.

4.78×108years

c.

5.12×109years

d.

4.78×109years

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