There are two atomic species $X$ and $Y$, such that

Atomic species	$X$	$Y$
Protons	$8$	$8$
Neutrons	$8$	$10$

Which of the following statements is true about $X$ and $Y$?

Match column I with column II and select the correct option from the given codes.

Which of the following are isobars?

Which of the following statements are correct regarding the elements given below?

${}_{19}{}^{39} \mathrm{K}, {}_{53}{}^{127}\mathrm{I}, {}_{17}{}^{35}\mathrm{Cl}, {}_{35}{}^{80}\mathrm{Br}, {}_{18}{}^{40}\mathrm{Ar}$

I The correct order of increasing proton number is $\mathrm{K}<\mathrm{Cl}<\mathrm{Br}<\mathrm{I}<\mathrm{Ar}$
II The correct order of increasing mass number is $\mathrm{Cl}<\mathrm{K}<\mathrm{Ar}<\mathrm{Br}<\mathrm{I}$
III There is difference in the orders of proton number and mass number.
IV The number of protons is equal to number of neutrons in all the given elements.