
Actually Welcome to the Concept of the Wave Optics.
Whenever the waves are out of phase they form a DESTRUCTIVE interference.
thus,
Destructive Interference occurs when two waves are out of phase.
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.
Choices 1, 2, and 4 . . . . . Yes
Choices 3 and 5 . . . . . No
Explanation:
The critical velocity is that velocity of liquid flow, up to which its flow is streamlined (laminar)& above which its flow becomes turbulent. It's denoted by Vc & it depends upon: Coefficient of viscosity of liquid (η) Density of liquid. Radius of the tube.