Which of the following statements is correct?

The element used by Rutherford in his famous scattering experiment was

In gel electrophoresis,the separated bands of $DNA$ are cut out and extracted from the gel piece. This step is called

Which of the following is an example of a heterogeneous catalysis reaction?

The uncertainties in the velocities of two particles $A$ and $B$ are $0.05 \ m \ s^{-1}$ and $0.02 \ m \ s^{-1}$ respectively. The mass of $B$ is five times that of mass $A$. What is the ratio of uncertainties $\left(\frac{\Delta x_A}{\Delta x_B}\right)$ in their positions?

The time period of a simple pendulum is $T$. When the length is increased by $10 \ cm$,its period is $T_1$. When the length is decreased by $10 \ cm$,its period is $T_2$. Then,the relation between $T, T_1$ and $T_2$ is