1.1. Phosphine, PH₃, is a gas formed by heating phosphorous acid, H₃PO₃, in the absence of air.

4H₃PO₃ (s) → PH₃ (g) + 3H₃PO₄ (s)

State the shape and bond angle in PH₃ (g).

1.2. 3.45 x 10^-2 mol of H₃PO₃ is completely decomposed at a pressure of 100 kPa and 210 °C.

Calculate the volume occupied, in cm³, by the phosphine gas produced.

Show your working.

1.3. 1.85 g of white phosphorus was reacted with 75.00 cm³ of 1.25 mol dm^-3 sodium hydroxide solution to make phosphine.

P₄ (s) + 3OH^- (aq) + 3H₂O (l) → PH₃ (g) + 3H₂PO₂^- (aq)

Show by calculation which reagent is in excess.

Show your working.

1.4. Use the information in part (c) to calculate the volume, in cm³, of phosphine that was produced at room conditions. Give your answer to 3 significant figures.