Step-by-step explanation:
Work done by gravity is given by the formula,
W =
......... (1)
It is known that when levels are same then height of the liquid is as follows.
h =
......... (2)
Putting value of equation (2) in equation (1) the overall formula will be as follows.
W =

=

= 0.689 J
Thus, we can conclude that the work done by the gravitational force in equalizing the levels when the two vessels are connected is 0.689 J.