Two radioactive substances $A$ and $B$ of mass numbers $200$ and $212$ respectively, show spontaneous $\alpha$-decay with the same $Q$ value of $1 \text{ MeV}$. The ratio of energies of $\alpha$-rays produced by $A$ and $B$ is . . . . . . .

When a nucleus with atomic number $Z$ and mass number $A$ undergoes a radioactive decay process:

$1 \text{ Curie}$ is equal to

$A$ radio nuclide $A_1$ with decay constant $\lambda_1$ transforms into a radio nuclide $A_2$ with decay constant $\lambda_2$. If at the initial moment the preparation contained only the radio nuclide $A_1$,then the time interval after which the activity of the radio nuclide $A_2$ reaches its maximum value is:

In the given reaction sequence ${ }_z X^A \rightarrow{ }_{z+1} Y^A \rightarrow{ }_{z-1} K^{A-4} \rightarrow{ }_{z-1} K^{A-4}$,identify the radioactive radiations emitted in order.

What is $\alpha-$,$\beta-$ and $\gamma-$decay? Write their general formulas.