MCQ
The ionization potentials of $Li$ and $K$ are $5.4$  and $4.3\, eV$ respectively. The  ionization potential of $Na$ will be .............. $\mathrm{eV}$
  • A
    $9.7$
  • B
    $1.1$
  • $4.9$
  • D
    cannot be calculated

Answer

Correct option: C.
$4.9$
c
$Li, Na, K$ are elements of same group ie $-IA$

In a group from top to bottom $I.P.$ value decreases.

So, the $I.P$ value of $Na$ will be lessthan Lithium and greater than Potassium

$I.P.$ value $=Li\,>Na\,>K$

So, it will be between $5.4$ and $4.3$ i.e $4.9 \,eV$.

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