Question

A box kept on a table is exerting $10N$ on it. In order to keep the box at its place, the table will exert a force $10N$.

Answer 1

The third law of motion states that when one object exerts a force on another object, the second object instantaneously exerts a force back on the first. These two forces are always equal in magnitude but opposite in direction.
Hence, the table will exert a force equal to $10N$.