Question

calculate the number of H- ion in 5.56g of BeH2

Answer 1

\(H^-\) as in hydride ions?

Answer 2

you'd want to, first, convert the mass given to moles, use: \(\sf moles=\dfrac{mass}{Molar~mass}\)

Then to formula units of \(BeH_2\), \(\sf moles=\dfrac{units}{Avogadro's ~number}\)