The atom will form two covalent bonds under normal circumstances.
The principle behind the number of bonds formed under normal circumstances is simple. The atoms wish to attain a stable atomic configuration by completing their valence shell by having 8 electrons (under most cases) in it. The best way to do this for the given atom is to gain 2 electrons, rather than try to lose its 6 electrons because losing so many electrons will require more energy.
The correct answer is A.
Gravitational force will attract any object with mass. It's why you're not floating in the air right now, but rather making contact with the ground. At the same time, since you have mass, you're also attracting other objects right now with gravitational force.
Answer:
There are now two oxygen atoms on the left and four on the right (in one N2O and three H2O's), so we balance the oxygen atoms by placing a 2 in front of the O2.