Elements $A$ and $B$ have the same mass number. Their atomic numbers are $27$ and $30$ respectively. If the mass number of $A$ is $57$,find the number of neutrons in $B$.

What is the number of nucleons present in an atom having $29$ electrons and $34$ neutrons in it?

The pair of atoms having the same number of neutrons is

The number of electrons in $[_{19}^{40}K]^{-1}$ is

Match the following columns:

$(i) \ _{26}Fe^{54}, \ _{26}Fe^{56}, \ _{26}Fe^{58}$	$(a) \ \text{Isotopes}$
$(ii) \ _1H^3, \ _2He^3$	$(b) \ \text{Isotones}$
$(iii) \ _{32}Ge^{76}, \ _{33}As^{77}$	$(c) \ \text{Isoelectronic}$
$(iv) \ _{92}U^{235}, \ _{90}Th^{231}$	$(d) \ \text{Isobars}$
$(v) \ _1H^1, \ _1D^2, \ _1T^3$

Give the symbol of the following species:
$(i)$ Number of electrons,protons,and neutrons are $10, 8$,and $8$ respectively.
$(ii)$ $Ca$ $(Z = 20)$ and nucleon number $= 40$.
$(iii)$ Species with mass number $25$,protons $12$ (magnesium),and electrons $10$.
$(iv)$ Species of Bromine in which $(Z = 35)$,electrons $36$,and neutrons $45$.
$(v)$ $+2$ positive and $-2$ negative ions that are isoelectronic with $Al^{3+}$ $(Z = 13)$.