NEET Chemistry The s-Block Elements Questions Solved

Alkali metals show-

(A) Only +1 oxidation state

(B) Only –1 oxidation state

(C) +1 and +2 oxidation states

(D) –1 and –2 oxidation states.

(A). Due to their low ionisation energies, these elements can easily form the univalent ions (M+ions) by losing the single ns1 electron. Since the unipositive ions have the stable noble gas configurations2 or s2p6 in the valence shell, the energy required to pull out another electron from the valence shell is very high i.e. the second ionisation energies of these metals are very high. Therefore, under
ordinary conditions, it is not possible for the metals to form M2+ ions. Therefore, they show only +1 oxidation state.

Difficulty Level:

  • 81%
  • 9%
  • 12%
  • 0%
Crack NEET with Online Course - Free Trial (Offer Valid Till August 27, 2019)