Question

$H_2$ is more reactive than $D_2$ because:

• A. $H_2$ is lighter than $D_2$.
• B. $H_2$ has low bond dissociation energy than $D_2$.
• C. $H_2$ is non radioactive while $D_2$ is radioactive.
• D. $D_2$ has two neutrons.

Answer 1

The correct option is B $H_2$ has low bond dissociation energy than $D_2$.

Larger amount of energy is required to break bonds between $D_2$.

The amount of energy required to break the bond present between atoms is called bond dissociation energy.

Hydrogen has three isotopes namely protium (H), deuterium (D) and tritium (T).

Among the three isotopes $H_2$ and $D_2$ are elements in which $H_2$ is composed of two hydrogen atoms whereas $D_2$ is composed of two Deuterium atoms.

The bond dissociation energy for $H_2=435.90$ and $D_2=443.40$.

As bond dissociation energy of $D_2$ is higher than $H_2$ then $H_2$ is more reactive than $D_2$

Hence, option B is correct.