Question

In reaction
$C_2{H}_{5}OH+HX\stackrel{Zn{X}_2}{\to }{C}_2{H}_{5}X+H_{2}O$
The order of reactivity of HX is-

• A. $HBr>HI>HCl$
• B. $HI>HCl>HBr$
• C. $HCl>HBr>HI$
• D. $HI>HBr>HCl$

Answer 1

The correct option is D $HI>HBr>HCl$

$C_2{H}_{5}OH+HX\stackrel{Zn{X}_2}{\to }{C}_2{H}_{5}X+H_{2}O$

HI has minimum bond dissociation energy and it is easy to break H−I bond whereas HCl has maximum bond dissociation energy and breaking of H−Cl bond is difficult. Greater is the ease of bond cleavage of halogen acids, greater is their reactivity.
Hence, the correct answer is option (d).