Atoms and Nuclei (NEET Physics): Questions 45 - 50 of 67

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Question number: 45

» Atoms and Nuclei » Nuclear Fission and Fusion

MCQ▾

Question

The energy released per fission of U 235 is about 200 MeV. A reactor using U 235 as fuel is producing 1000 kilowatt power. The number of U 235 nuclei undergoing fission per sec is, approximately-

Choices

Choice (4) Response

a.

3 × l0 16

b.

2 × 10 8

c.

10 6

d.

931

Passage

Read the passage given below and answer the questions that follow:

In a living organism, the quantity of C 14 is the same as in the atmosphere. But in organisms which are dead, no exchange takes place with the atmosphere and by measuring the decay rate of 14 C in the old bones or wood, the time taken for the activity to reduce to this level can be calculated. This gives the age of the wood or bone.

Given: T 1/2 for 14 C is 5370 years and the ratio of C14C12 is 1.3 ⨯ 10 -12.

Question number: 46 (1 of 3 Based on Passage) Show Passage

» Atoms and Nuclei » Radioactive Decay Law

MCQ▾

Question

The decay rate in another piece is found to be 0.30 Bq per gm then we can conclude,

Choices

Choice (4) Response

a.

The observed decay is not that of 14 C alone

b.

There is a statistical error

c.

he sample is very recent

d.

All a. , b. and c. are correct

Question number: 47 (2 of 3 Based on Passage) Show Passage

» Atoms and Nuclei » Radioactive Decay Law

MCQ▾

Question

The decay rate of 14 C in l gm of carbon in a living organism is,

Choices

Choice (4) Response

a.

25 Bq

b.

0.25 Bq

c.

2.5 Bq

d.

5 Bq

Question number: 48 (3 of 3 Based on Passage) Show Passage

» Atoms and Nuclei » Radioactive Decay Law

MCQ▾

Question

If in an old sample of wood of 10g the decay rate is 30 decays per minute, the age of the wood is

Choices

Choice (4) Response

a.

15300 years

b.

13310 years

c.

1000 years

d.

50 years

Question number: 49

» Atoms and Nuclei » Radioactivity

MCQ▾

Question

For thorium A = 232 and Z = 90, at the end of some radioactive disintegrations we obtain an isotope of lead with A = 208 and Z = 82. Then the number of α and β particles emitted are,

Choices

Choice (4) Response

a.

α=5,β=5

b.

α=6,β=3

c.

α=4,β=6

d.

α=6,β=4

Question number: 50

» Atoms and Nuclei » Radioactivity

Assertion-Reason▾

Assertion (Ꭺ)

Electron capture occurs more often than positron emission in heavy elements.

Reason (Ꭱ)

Heavy elements exhibit radioactivity.

Choices

Choice (4) Response

a.

Ꭺ is true but Ꭱ is false

b.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

c.

Ꭺ is false but Ꭱ is true

d.

Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ

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