Thank you for reporting, we will resolve it shortly
Q.
An object is kept on a smooth inclined plane of $1 $ in $ l. $ The horizontal acceleration to be imparted to the inclined plane so that the object is stationary relative to incline is
Here, $\sin \theta=\frac{1}{l}$
When horizontal acceleration is imparted to the inclined plane, then a pseudo acceleration acts on the object. For the object to remain stationary relative to the incline, we have
$a=g \tan \theta=g \frac{1}{\sqrt{l^{2}-1}}$
or $a=\frac{g}{\sqrt{l^{2}-1}}$