Is the work done by the gravitational force on an object falling freely under gravity positive,negative,or zero?

When a body moves in a circular path,no work is done by the centripetal force since

$A$ horizontal force of $5 \,N$ is required to maintain a velocity of $2 \,m/s$ for a block of $10 \,kg$ mass sliding over a rough surface. The work done by this force in one minute is $J$.

$A$ chain of mass $4 \ kg$ and length $2 \ m$ is hanging such that one-fourth of its length is hanging over the edge of a table. The work done to pull the hanging part onto the table is . . . . . . $J$. (Take $g = 10 \ m/s^2$)

$A$ force $\vec{F} = 3\hat{i} + c\hat{j} + 2\hat{k}$ acting on a particle causes a displacement $\vec{s} = -4\hat{i} + 2\hat{j} + 3\hat{k}$. If the work done is $6\,J$,then the value of $c$ is:

Define work exerted by force.