Question

Two elements having same number of protons and electrons but different number of neutrons

Answer 1

so in that case, two atoms with same number of protons but different numbers of neutrons are actually atoms of the same element. they are called"isomers" of one another. Example, Carbon l2 and Carbon l4. Both have 6 protons, but C-12 has 6 neutrons and C-14 has 8 neutrons