In the nuclear reaction $_{92}U^{238} \to _{Z}Th^{A} + _{2}He^{4}$,the values of $A$ and $Z$ are:

The $A_{92}U^{238}$ nucleus decays to a $Pb^{214}_{82}$ nucleus. The number of $\alpha$ and $\beta^{-}$ particles emitted are:

Assertion : The ionising power of $\beta$-particle is less compared to $\alpha$-particles but their penetrating power is more.
Reason : The mass of $\beta$-particle is less than the mass of $\alpha$-particles.

$A$ radioactive nucleus of mass number $A$,initially at rest,emits an $\alpha$-particle with a speed $v$. The recoil speed of the daughter nucleus will be

The rate of disintegration of a radioactive sample can be increased by:

$A$ radioactive element $_{90}X^{238}$ decays into $_{83}Y^{222}$. The number of $\beta$-particles emitted is: