Atoms and Nuclei-Radioactivity (KVPY Stream SB-SX (Class 12 & 1st Year BSC) Physics): Questions 1 - 2 of 2

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Question number: 1

» Atoms and Nuclei » Radioactivity

Appeared in Year: 2010

MCQ▾

Question

A nucleus has a half-life of 30 minutes. At 3 PM its decay rate was measured as 1, 20, 000countssec . What will be the decay rate at 5 PM?

Choices

Choice (4) Response

a.

60, 000countssec

b.

30, 000countssec

c.

1, 20, 000countssec

d.

7, 500countssec

Question number: 2

» Atoms and Nuclei » Radioactivity

Appeared in Year: 2015

MCQ▾

Question

Carbon -11 decays to boron -11 according to the following formula.

CC+e++νe+0.96MeV

Assume that positrons (e+) produced in the decay combine with free electron in the atmosphere and annihilate each other almost immediately. Also assume that the neutrinos (νe) are massless and do not interact with the environment. At t = 0 we have 1 µg of C . If the half-life of the decay process is t0, the net energy produced between time t = 0 and t = 2t0 will be nearly,

Choices

Choice (4) Response

a.

8×1018MeV

b.

4×1016MeV

c.

4×1018MeV

d.

8×1016MeV

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