The successive ionisation enthalpies of an element $X$ in $(kJ \ mol^{-1})$ are $1012$,$1907$,$2955$,$4955$,$6275$ and $21,260$ respectively. The element $X$ is:

The correct order of second ionisation potentials $(IP)$ of $Ca$,$Ba$ and $K$ is

The ionisation potentials of $Li$ and $K$ are $5.4 \ eV$ and $4.3 \ eV$ respectively. The ionisation potential of $Na$ will be ................ $eV$.

Mercury is the only metal which is liquid at $0 \, ^oC$. This is due to its:

The incorrect statement among the following is:

The $1^{\text{st}}$,$2^{\text{nd}}$,and $3^{\text{rd}}$ ionization enthalpies $I_1, I_2$,and $I_3$ of four atoms with atomic numbers $n, n+1, n+2$,and $n+3$,where $n < 10$,are tabulated below. What is the value of $n$?

Atomic number	$I_1$ $(kJ/mol)$	$I_2$ $(kJ/mol)$	$I_3$ $(kJ/mol)$
$n$	$I_1$	$I_2$	$I_3$
$n+1$	$1681$	$3374$	$6050$
$n+2$	$2081$	$3952$	$6122$
$n+3$	$496$	$4562$	$6910$
$n+4$	$738$	$1451$	$7733$