Which statement is correct?

the number of electrons of a neutral atom always equals the number of protons.
the number of neutrons always equals the number of protons.
the number of neutrons always equals the number of electrons.
atomic weight is identical to atomic mass.

The first and last statements are correct. In a neutral atom, number of electrons are always equal to number of protons or atomic number. Atomic weight is also called or referred to as atomic mass. In a neutral atom, the number of neutrons is equal to atomic mass minus atomic number or electrons or protons. 

Covalent bond is the correct answer