RRB Group-D Model Paper 14 with answers for online practice

As seen from the above figure,
The diagonal AC = $10\sqrt{2}$
Now ABC forms a right angled triangle with AB = BC
By Pythagoras theorem,
$\mathit{A}{\mathit{B}}^2+\mathit{B}{\mathit{C}}^2=\mathit{A}{\mathit{C}}^2$
$2\mathit{A}{\mathit{B}}^2=100\times 2$
$\mathit{A}{\mathit{B}}^2=100$
AB = 10
Perimeter of a square = 4 AB = 40 cm