How many isotopes has hydrogen?

Which of the following electrons configurations correctly represents an inert element?

What type of reaction is represented by the following equation?\(\frac{2}{1}\)D\(\frac{3}{1}\)H → \(\frac{4}{4}\)He + \(\frac{1}{0}\)n + energy

An element with the electron configuration of 1s ²2s ²2p ⁶ would have a combining power of