Question

an atom is electrically neutral how can it becomes charged ​

Answer 1

Atoms are electrically neutral because they have equal numbers of protons (positively charged) and electrons (negatively charged). If an atom gains or loses one or more electrons, it becomes an ion. If it gains one or more electrons, it now carries a net negative charge, and is thus "anionic.

Answer 2

atoms having same no of electron and proton.so by increasing the no of electron it will be charged