Wavefront with point X and Y on trough and crest respectively

Answer: Option B

Wavefront is an imaginary line that joins all identical adjacent points that are in phase.

So if you assume the circular wavefront that connects Y is crest, than X will be a trough.

Weight-mass graph - Find g on different planets

Answer: Option A

W = mg, where g is the gravitational field strength.

g = W/m, hence g is the gravitational force (pull) acting per unit mass of an object.

In addition, in the weight-mass graph, the gradient represents the g.

I.e the steeper the line, the higher the g for the planet.

Mass is the amount of matter in the body. So for this question, it is important to know that mass remains constant whether it is on planet P or Q.

Why is there an opposing force on the coil when the circuit is closed?