Complete the following gaps in the given table:

Elements	Protons	Electrons	Neutrons	Atomic Number	Mass Number
A	–	–	10	8	–
B	15	–	–	–	31
C	1	–	–	–	3
D	–	11	12	–	–

We know that the number of protons = Atomic number

Number of protons = Number of electrons

Mass number = Number of protons + number of neutrons

Using these relationships, we can fill up these gaps as follows.