# NEET (NTA)-National Eligibility cum Entrance Test (Medical) Physics: Questions 1517 - 1521 of 2320

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## Passage

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 is 1.3 ⨯ 10 -12.

## Question number: 1517 (2 of 3 Based on Passage) Show Passage

Edit
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.

5 Bq

c.

2.5 Bq

d.

0.25 Bq

## Question number: 1518 (3 of 3 Based on Passage) Show Passage

Edit
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.

1000 years

b.

50 years

c.

13310 years

d.

15300 years

## Question number: 1519

Edit
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.

b.

c.

d.

## Question number: 1520

» Thermodynamics » Laws of Thermodynamics » Second Law of Thermodynamics

Edit
Assertion-Reason▾

### Assertion (Ꭺ)

A room can be warmed by opening the door of a refrigerator in a closed room

### Reason (Ꭱ)

Head flows from lower temperature (refrigerator) to higher temperature (room).

### Choices

Choice (4)Response

a.

Both Ꭺ and Ꭱ are false

b.

Ꭺ is false but Ꭱ is true

c.

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

d.

Ꭺ is true but Ꭱ is false

## Question number: 1521

Edit
Assertion-Reason▾

### Assertion (Ꭺ)

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

### Choices

Choice (4)Response

a.

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

b.

Ꭺ is true but Ꭱ is false

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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