Question

what is the number of an outermost shell of an atom?? ​

Answer 1

Answer:

Each shell of an atom can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on.

Answer 2

Answer:

the number of an outermost shell of an atom depends upon its atomic number