The correct order of reducing abilities of hydrides of V group elements is

The correct order of reducing abilities of hydrides of V group elements is
  1. $\mathrm{NH}_3 < \mathrm{PH}_3 < \mathrm{AsH}_3 < \mathrm{SbH}_3 < \mathrm{BiH}_3$
  2. $\mathrm{NH}_3>\mathrm{PH}_3>\mathrm{AsH}_3>\mathrm{SbH}_3>\mathrm{BiH}_3$
  3. $\mathrm{NH}_3 < \mathrm{PH}_3>\mathrm{AsH}_3>\mathrm{SbH}_3>\mathrm{BiH}_3$
  4. $\mathrm{SbH}_3>\mathrm{BiH}_3>\mathrm{AsH}_3>\mathrm{NH}_3>\mathrm{PH}_3$

Solution

The reducing character of the hydrides of group V elements depends upon the stability of hydrides. With progressive decrease in stability, the reducing character of hydrides increases as we move down the group. Thus, ammonia, being stable, has least reducing ability. The order of reducing abilities of $\mathrm{V}$ group hydrides is $ \mathrm{NH}_3 < \mathrm{PH}_3 < \mathrm{AsH}_3 < \mathrm{SbH}_3 < \mathrm{BiH}_3 $

Asked in: AP EAMCET 2008

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