Compared to the atomic radius of a sodium atom, the atomic radius of a magnesium atom is smaller. The smaller radius is primarily a result of the magnesium atom having A) more principal energy levels B) a larger nuclear charge C) fewer principal energy levels D) a smaller nuclear charge

 B) a larger nuclear charge

Explanation:

Atomic radius of an atom is defined as the total distance from the nucleus to the outermost shell of the atom.

Sodium and magnesium lies in the same period and magnesium lies to the right of sodium. They have same number of principle shell.

As moving from left to right in a period, more and more electrons get added up in the same principle shell and the attraction between the last electron and nucleus increases , which results in the larger nuclear charge and thus shrinkage in the size of an atom. Thus, decreasing the atomic radii of the atom on moving towards right of the periodic table.

plasma is the state of matter where the substance is ionized and has no definite shape or volume. the fact of being ionized makes the substance a good electrical conductor.

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.