Physics

Question 1

1A radioactive isotope has a half-life of 13.86 s. Find its decay constant.

Hard

A. 0.036 s⁻¹ B. 0.05 s⁻¹ C. 20 s⁻¹ D. 9.605 s⁻¹

Question 2

2The strong nuclear force

Medium

A. holds electrons in orbit B. holds nucleons together in the nucleus C. repels protons D. acts over long distances

Question 3

3A sample contains 8000 radioactive nuclei. After 3 half-lives, the number remaining is ___.

Easy

Your answer (fill in the blank)

Question 4

4How much energy is released when 0.01 kg of mass is converted to energy? (c = 3 × 10⁸ m/s)

Medium

A. 9 × 10¹⁴ J B. 3 × 10⁶ J C. 9 × 10¹³ J D. 9 × 10⁶ J

Question 5

5Radioactive decay is

Easy

A. predictable for each nucleus B. controlled by temperature C. random and spontaneous D. speeded up by pressure

Question 6

6A chain reaction occurs when

Medium

A. gamma rays are absorbed B. fusion stops C. neutrons released by fission cause further fissions D. electrons are emitted

Question 7

7The decay constant λ is related to half-life T½ by

Hard

A. T½ = 1/λ² B. T½ = λ/0.693 C. T½ = 0.693λ D. T½ = 0.693/λ

Question 8

8Uranium-235 is used as fuel in nuclear reactors.

Easy

A. True B. False

Question 9

9Einstein's mass–energy relation is

Easy

A. E = mc B. E = hf only C. E = mc² D. E = ½mv²

Question 10

10A sample contains 1000 radioactive nuclei. After 2 half-lives, the number remaining is ___.

Easy

Your answer (fill in the blank)