The n-h bond in ammonia is polar because

a: nitrogen occupies more space than hydrogen.

b: hydrogen is much more electronegative than nitrogen.

c: it is a hydrogen bond.

d: it is an ionic bond.

e: nitrogen is much more electronegative than hydrogen.

The answer to your question is letter E. Nitrogen is much more electronegative than hydrogen.

Explanation:

Talking about bonding, we must know that there are two main types of bonds.

- Ionic bonds: these bonds are formed when we combine metal and a nonmetal and the electronegativity between these elements is higher than 1.7.

- Covalent bonds are formed when two nonmetals are combined. There are two kinds of covalent bonds:

  a) Nonpolar, the electronegativity between the nonmetals is between 0 and 0.5.

  b) Polar, the electronegativity between the nonmetals is between 0.5 and 1.7.

In this problem, the difference of electronegativity between nitrogen (3.04) and hydrogen (2.2) is 0.84, then this molecule has a polar bond.