Negatively charged particles found in shells around the nucleus of a particular atom:
A. are equal to the number of protons
B. are equal to the number of neutrons
C. are equal to the number of protons plus the number of neutrons in the nucleus
D. are equal to the atomic mass

A. are equal to the number of protons.

Explanation:

In an electrically neutral atom the number of protons in the nucleus balances the number of electrons. protons are positively charge and electrons negatively charged and for this their charges cancel out and makes the atom to be in a neutral state.

Option B is wrong as the number of neutrons is different from the number of protons an electrons.

option C is also wrong because, the sum of protons and neutron makes up the atomic mass of the atom. This is different from the atomic number which is the number of protons in an atom. For this same reason option D is wrong.

So the correct option is option A.

layer a is the exosphere and layer b is the thermosphere.   is the answer i think but i hope this .

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.