Write an equation for the reaction of phosphorus ($P_4$) with an excess supply of oxygen to form phosphorus(V) oxide ($P_4{O}_{10}$).

Describe a test you could carry out in a test tube to distinguish between solid sodium oxide and solid aluminium oxide.

State the type of crystal structure shown in magnesium oxide and in sulfur trioxide.

Explain, in terms of structure and bonding, why magnesium oxide has a much higher melting point than sulfur trioxide.

Write an equation for the reaction of sulfur trioxide (${SO}_3$) with excess sodium hydroxide solution.

Write an equation for the reaction of an excess of magnesium oxide with phosphoric acid ($H_3{PO}_4$).

Draw the displayed formula of the undissociated acid formed when phosphorus(V) oxide reacts with water.