Questions in atomic-structure

Select	Question
	Compared with an atom of atomic weight $12$ and atomic number $6$,the atom of atomic weight $13$ and atomic number $6$
	In the nucleus of$_{20}C{a^{40}}$ there are
	$N{a^ + }$ ion is isoelectronic with
	$Ca$ has atomic no. $20$ and atomic weight $40$. Which of the following statements is not correct about $Ca$ atom
	Pick out the isoelectronic structures from the following$\mathop {CH_3^ + }\limits_{\rm{I}} $ $\mathop {{H_3}{O^ + }}\limits_{{\rm{II}}} $ $\mathop {N{H_3}}\limits_{{\rm{III}}} $ $\mathop {CH_3^ - }\limits_{{\rm{IV}}} $
	Number of electrons in $ - CON{H_2}$ is
	The atomic number of an element having the valency shell electronic configuration $4{s^2}4{p^6}$ is
	The present atomic weight scale is based on
	Isoelectronic species are
	If the atomic weight of an element is $23$ times that of the lightest element and it has $11$ protons,then it contains