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 correct statement is The number of electrons of a neutral atom is always equals to the number of protons.

Explanation:

An atom contain nucleus in its centre that have positively charged  particle called protons and neural particle neutron. .Electrons are present outside the nucleus in various electron cloud.Electrons are negatively charged.

              The number of electrons are equal to the number of proton.As a result the positive charge of the protons neutralizes the negative charge of the electron that"s why an atom is always neutral.

the answer to you question is   jet streams

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds