$A$ radioactive element ${ }_{92}^{242} X$ emits two $\alpha$ particles,one electron and two positrons. The product nucleus is represented by ${ }_{P}^{234} Y$. The value of $P$ is

In the following nuclear reaction,$D \xrightarrow{\alpha} D_{1} \xrightarrow{\beta^-} D_{2} \xrightarrow{\alpha} D_{3} \xrightarrow{\gamma} D_{4}$. The mass number of $D$ is $182$ and the atomic number is $74$. The mass number and atomic number of $D_{4}$ respectively will be:

$A$ radioactive nucleus is initially at rest. It decays by emitting an electron and a neutrino at right angles to each other. The momentum of the electron is $3.2 \times 10^{-23} \ kg \cdot m/s$ and the momentum of the neutrino is $6.4 \times 10^{-23} \ kg \cdot m/s$. What is the direction of the recoil of the nucleus with respect to the direction of the electron?

Which ray contains positively charged particles?

$A$ nucleus of an element ${}_{84}X^{202}$ emits an $\alpha$-particle first,a $\beta$-particle next,and then a gamma photon. The final nucleus formed has an atomic number:

$A$ radioactive substance emits