Physics

Radioactivity and Nuclear Decay

74 Questions

Radioactivity and nuclear decay problems revolve around half-life calculations, decay rates, and nuclear stability. These topics are crucial for general science preparation in many exams. Regular practice helps in quickly solving complex decay chain numericals.

half life calculationnuclear stabilitydecay rate constantalpha beta decay

Radioactivity and Nuclear Decay Questions

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

One mole of radium has an activity of 1/3.7 killo curie. Its decay constant will be 

  1. $\frac{1}{6}\times -10s^{-1}$
  2. $ 10^{-10}s^{-1}$
  3. $ 10^{-11}s^{-1}$
  4. $ 10^{-8}s^{-1}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Number of mole of radium, $n=1$

The number of nuclei of radium, $N={{N} _{a}}=avagdaro\,\,number=6.023\times {{10}^{23}}$

Activity, $A=\lambda N$

$ \because 1\,\,curie=3.7\times {{10}^{10}}\,decay/\sec  $

$ \dfrac{1}{3.7}\,kilocurie=0.27\,kilocurie=9.99\times {{10}^{12}}\,dacay/\sec  $

So, $\lambda =\dfrac{A}{N}=\dfrac{9.99\times {{10}^{12}}}{6.023\times {{10}^{23}}}=1.65\times {{10}^{-11}}\,$

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The amount of $U ^ { 235 }$ in kg which is to be used per hour in a nuclear reactor of capacity $100$ ($E = 200 MeV/fission$)

  1. $0.45 \times 10^{-5}$
  2. $4.5 \times 10^{-5}$
  3. $4.5 \times 10^{5}$
  4. $45 \times 10^{-5}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Power = 100 MW = 10^8 J/s. Energy per fission = 200 MeV = 3.2 * 10^-11 J. Fissions per second = 10^8 / (3.2 * 10^-11) = 3.125 * 10^18. Mass per second = (3.125 * 10^18 * 235) / (6.022 * 10^23) = 1.22 * 10^-3 g/s. Multiplying by 3600 seconds gives the hourly rate.

Multiple choice

A radioactive atom's half life

  1. is constant

  2. acts like a clock

  3. never changes

  4. all of these answers
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The half-life of a radioactive isotope is a constant property that does not change over time, making it a reliable tool for dating materials.

Multiple choice

What is the term used to describe the rate at which a radioactive substance decays?

  1. Half-Life

  2. Decay Constant

  3. Activity

  4. Specific Activity
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Half-life is the time it takes for half of the atoms in a radioactive substance to decay.

Multiple choice

The half-life of Carbon-14 is approximately:

  1. 5,730 years

  2. 1,600 years

  3. 4,500 years

  4. 10,000 years
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carbon-14 has a half-life of approximately 5,730 years.

Multiple choice

What is the half-life of carbon-14?

  1. 5,730 years

  2. 10,000 years

  3. 15,000 years

  4. 20,000 years
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The half-life of carbon-14 is 5,730 years, which means that it takes 5,730 years for half of the carbon-14 in a sample to decay.

Multiple choice

Which of the following differential equations models radioactive decay?

  1. $$\frac{dN}{dt} = -\lambda N$$
  2. $$\frac{dN}{dt} = \lambda N$$
  3. $$\frac{dN}{dt} = -\lambda N^2$$
  4. $$\frac{dN}{dt} = \lambda N^2$$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Radioactive decay is characterized by a constant rate of decay proportional to the amount of radioactive material present.

Multiple choice

What is the half-life of a radioactive substance?

  1. The time it takes for half of the substance to decay

  2. The time it takes for all of the substance to decay

  3. The time it takes for the substance to double in amount

  4. The time it takes for the substance to triple in amount
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The half-life is the time it takes for half of the radioactive substance to decay.

Multiple choice

What is the half-life of a radioactive substance?

  1. The time it takes for half of the substance to decay

  2. The time it takes for all of the substance to decay

  3. The time it takes for the substance to become stable

  4. The time it takes for the substance to become radioactive
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The half-life of a radioactive substance is the time it takes for half of the substance to decay.

Multiple choice

The half-life of a drug is the time it takes for the concentration of the drug in the body to:

  1. Double

  2. Halve

  3. Triple

  4. Quadruple
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The half-life of a drug is the time it takes for the concentration of the drug in the body to halve.