Q10 / 54 · KVPY 2017 (5 Nov SA) · Chemistry

The atomic radii of $\mathrm{Li}, \mathrm{F}, \mathrm{Na}$ and Si follow the order.

  • A
    $\mathrm{Si}>\mathrm{Li}>\mathrm{Na}>\mathrm{F}$
  • B
    $\mathrm{Li}>\mathrm{F}>\mathrm{Si}>\mathrm{Na}$
  • C
    $\mathrm{Na}>\mathrm{Si}>\mathrm{F}>\mathrm{Li}$
  • Correct answer
    D
    $\mathrm{Na}>\mathrm{Li}>\mathrm{Si}>\mathrm{F}$

Solution

Among the given elements Li and Na belong to group 1, i.e. they are alkali metals. So, they will have maximum atomic radii. Between Li and Na, Na will have the largest atomic radii. This is because as we move down the group atomic radii increases. Si belongs to group 14 and \(\mathrm{F}\) belongs to group 17 . So, as we move from left to right in period the atomic radii decreases. Thus, Si will have large atomic radii than \(\mathrm{F}\) but less than Li. So, the correct order of atomic radii of given elements is, Na > Li > Si > F.

Hence, the correct answer is option: 'D'.

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