Answer
The predicted $As-Cl$ bond length is $2.24 \dot{A}$.
Work Step by Step
If the $As-As$ bond length is 2.48 then the atomic radii of $As$ is half that, or $1.24$.
If the $Cl-Cl$ bond length is 1.99 then the atomic radii of $As$ is half that, or 0.995. Since the given length is given to the hundredths, the computed radii should be rounded to the hundredth. $0.995\approx1.00$
The predicted $As-Cl$ bond length is the sum of their atomic radii.
$1.24+1.00=2.24$
