$({}_{32}Ge^{76}, {}_{34}Se^{76})$ and $({}_{14}Si^{30}, {}_{16}S^{32})$ are examples of

In the two elements, ${ }_{Z_1} A^{M_1}$ and ${ }_{Z_2} B^{M_2}$, the following relations are true. $M_1 \neq M_2$ and $Z_1 \neq Z_2$ but $M_1-Z_1=M_2-Z_2$. These elements are ($M$ is atomic weight, $Z$ is atomic number)

The spectrum of $He$ is expected to be similar to

Match the following atomic species with their correct classification:

$(i) \ { }_{26} Fe ^{54}, { }_{26} Fe ^{56}, { }_{26} Fe ^{57}, { }_{26} Fe ^{58}$	$(a)$ Isotopes
$(ii) \ { }_1 H ^3, { }_2 He ^3$	$(b)$ Isotones
$(iii) \ { }_{32} Ge ^{76}, { }_{33} As ^{77}$	$(c)$ Isodiaphers
$(iv) \ { }_{92} U ^{235}, { }_{90} Th ^{231}$	$(d)$ Isobars
$(v) \ { }_1 H ^1, { }_1 D ^2, { }_1 T^3$

What are the similarities and differences between $Mg$ and $Mg^{2+}$?

An isotone of $_{32}^{76}Ge$ is (one or more are correct)