B is correct answer.
The atomic mass is the most important because it tells you the number of electrons.
Hope it helped you.
-Charlie
Answer:

Explanation:
As it is given that flow rate in the pipe is 20 cm^3/s
so we have

at the upper end the area is given as


Also at the other end


now the speed at two ends is given as




now by Bernoulli's theorem we have

now we have

Now we have

Answer:
Catastrophic theories
Explanation:
The theory of catastrophe is a collection of methods used to analyze and describe the ways in which a system can experience sudden significant behavioral changes when one or more of the variables that govern it are continuously modified.
Georges Louis de Buffon suggested in 1745 the first destructive theory — that a comet pulled material from the Sun to form the planets.
Therefore the answer is -
Catastrophic theories
6 months with no sunrise and the other 6 without a sunset, at some places on Earth, are the result of the orientation of Earth's axis.