How will the amount of thermal energy required to change each substance from a liquid to a gas differ?

a) water and mercury will require the same amount of energy to change from liquid to gas.
b) mercury will require a greater amount of energy to change from liquid to gas than water.
c) neither water nor mercury will require any energy to change from liquid to gas as long as they are each at their boiling temperatures.
d) water will require a greater amount of energy to change from liquid to gas than mercury.

How does the image distance (di) of a convex lens compare with the image distance of a concave lens? a. the image distance of the convex lens is positive, and that of the concave lens is negative. b. both are negative for a virtual image. c. both are positive for a virtual image d. the image distance of the convex lens is negative, and that of the concave lens is positive.

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

Consider a one meter long horizontal pipe with a constant 100 cm^2 cross sectional area. water flows rightward into the pipe at x = 0 with flow velocity 02m/sec at every point within the pipe intake area. at x=1, the rightward flow rate is 0.192 m/sec. assume the water is a conserved quantity in the pipe, so there must be a leak (a sink) somewhere in the pipe. 1. compute net volumetric flow of the source if the system to be in equilibrium. 2. now assume the pipe in the problem has no leaks. compute the net volumetric rate of change for the system.