a. Describe the acid–base nature of the solutions obtained when the following compounds are added to water. Use equations to illustrate your answers.

i. Sodium chloride

ii. Sulfur trioxide

iii. Sodium oxide

iv. Phosphorus(V) chloride.

b. i. Write an equation for the reaction of magnesium with cold water.

ii. Predict and explain the pH of the resulting solution.

c. When magnesium is added to water, the reaction is very slow. In contrast, phosphorus(III) chloride (PCl₃) is a liquid that reacts vigorously with water. One of the products of this reaction is H₃PO₃, which forms in solution.

i. Write an equation, including state symbols, showing the reaction of phosphorus(III) chloride with water.

ii. Predict the pH of the solution obtained.

iii. State one observation a student watching the reaction would make.