Calculate the number of alumnium ions present in 0.051 g of aluminium oxide.

Calculate the number of moles is 60g NaOH.

Calculate the number of molecules of sulphur (S_8) present in 16g of solid sulphur.

Calculate the number of moles in 10g of CH_4 .

Sodium crystallizes in a body-centred cubic (bcc) unit cell. Calculate the approximate number of unit cells in 9.2g of sodium. (Atomic mass of Na = 23u).

Answer either: Calculate the number of unpaired elec-trons in the gaseous ion Cr^(3+) .