Hello Candidate,

In the first question, a particle Executes SHM of amplitude A. It's Velocity will be maximum at the point of maximum displacement which is equal to +-A, velocity will be zero at the equilibrium point. The acceleration of the particle will be maximum at the equilibrium point will be zero at maximum displacement.

The mercury collects itself upon falling on a surface because of its high contact angle which is approximately equal to 135 degrees.

Hope This information helps you!!