In which of the following decays the atomic number decreases?

Q. In which of the following decays the atomic number decreases?
(a) α-decay
(b) β⁺-decay
(c) β⁻-decay
(d) γ-decay

Q. STATEMENT - 1 : ${}_Z{X}^A$ undergoes 2 $\alpha$ decays, 2$\beta$ decays (negative $\beta$) and 2 decays. As a result the daughter product is
${}_{Z-2}{Y}^{A-8}.$
STATEMENT -2 : In $\alpha$ decay the mass number decreases by 4 unit and atomic number decreases by 2 unit. In $\beta$ decay (negative $\beta$) the mass number remains unchanged and atomic number increases by 1 unit. In $\gamma$ decay, mass number and atomic number remains unchanged.

Q. Assertion :${{}_{z}X}^A$ undergoes $2$ $\alpha$- decays, $2$ $\beta$- decays (negative $\beta$) and $2$ $\gamma$-decays. As a result , the daughter product is ${{}_{z-2}Y}^{A-8}$ Reason: In $\alpha$- decay, the mass number decreases by $4$ unit and atomic number decreases by $2$ unit. In $\beta$- decay (negative $\beta$), the mass number remains unchanged and atomic number increaess by $1$ unit. In $\gamma$-decay, mass number and atomic number remain unchanged

Q. Assertion :${}_Z{X}^4$ undergoes $2\alpha -decays,2\beta -decays$ (negative $\beta$), and $2\gamma -decays$. As a result, the daughter product is ${}_{z-2}{Y}^{A-B}$ Reason: In $\alpha -decay$, the mass number decreases by 4 unit and atomic number decreases by 2 unit. In $\beta -decay$ (negative $\beta$), the mass number remains unchanged and atomic number increases by 1 unit. In $\gamma -decay$, mass number and atomic number remain unchanged.

Q. In which of the following decays the element does not change?
(a) α-decay
(b) β⁺-decay
(c) β⁻-decay
(d) γ-decay