A nucleus of uranium decays at rest into nuclei of thorium and helium. Then:

1.	The nucleus helium has more kinetic energy than the thorium nucleus
2.	The helium nucleus has less momentum than the thorium nucleus
3.	The helium nucleus has more momentum than the thorium nucleus
4.	The helium nucleus has less kinetic energy than the thorium nucleus

Fission of nuclei is possible because the binding energy per nucleon in them-

1.  Decreases with mass number at low mass numbers

2.  Increases with mass number at low mass numbers

3.  Decreases with mass number at high mass numbers

4.  Increases with mass number at high mass numbers

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an:

In the radioactive decay process, the negatively charged emitted β-particles are:

Two radioactive substances A and B have decay constants 5λ and λ respectively. At t = 0, they have the same number of nuclei. The ratio of the number of nuclei of A to those of B will be $\frac{1}{e^2}$ after a time interval:

1. $\frac{1}{4\lambda }$

2. $4\lambda$

3. $2\lambda$

4. $\frac{1}{2\lambda }$

In a radioactive material, the activity at time t₁ is R₁ and at a later time t₂, it is R₂. If the decay constant of the material is λ, then:

1. $R_1=R_2{e}^{\lambda (t_1\mathit{+}{t}_2)}$

2. $R_1=R_2{e}^{-\lambda (t_1-t_2)}$

3. $R_1=R_2(t_1-t_2)$

4. $R_1=R_2$