Decrease in atomic number is observed during

When a $\beta $-particle is emitted from the nucleus of an element,then:

Which statement is incorrect?

$\gamma$ rays are

The number of $\alpha$ and $\beta$-particles emitted in the nuclear reaction $_{90}^{228}Th \to _{83}^{212}Bi$ are respectively:

An atom has a mass number of $232$ and an atomic number of $90$. How many $\alpha$-particles should it emit after the emission of two $\beta$-particles,so that the resulting atom has a mass number of $212$ and an atomic number of $82$?