As a 1-gram sample of H2O(1) changes to H2O(g)
at 100°C, the potential energy of the molecules
A. decreases
B.
increases
C. remains the same

Option B

Explanation:

Changing of a substance from liquid to a gas, is known as vaporization. During vaporization a substance absorbs thermal energy. The forces between particle is very weak and hence they gain potential energy. Thus, while changing from liquid to gas, energy gets absorbed to increase the potential energy. This energy is known as latent heat of vaporization.

Hence, option B is correct

n has four pairs of electrons in the valence shell, electrons repel one another ,n has 7 protons in its nucleus, and since n has 7 protons, it must fill the second shell, giving it 4 pairs of electrons. the electrons form 3 bonds and 1 lone pair of electrons. each pair of electrons repels the other pairs, so they are equally far apart.

so all of the above

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.