Water from natural sources contains dissolved substances which are not pollutants, such as mineral salts.

1. (a)Name another substance found naturally in water which is not a mineral salt or a pollutant.[1]
2. (b)When lithium reacts with water, aqueous lithium hydroxide, LiOH, and hydrogen are formed. Construct the equation for this reaction.[1]
3. (c)(i)Sodium and potassium react with water in a similar way to lithium. Explain, in terms of their electronic configuration, why lithium, sodium and potassium all react in a similar way.[1]
4. (c)(ii)Describe the trend in reactivity of the Group I elements lithium, sodium and potassium.[1]
5. (d)Water and oxygen are formed when aqueous hydrogen peroxide decomposes. 2H2O2(aq) → 2H2O(l) + O2(g) Calculate the maximum volume of oxygen, at room temperature and pressure, which is produced by the complete decomposition of a solution containing 16.0g of hydrogen peroxide. Give your answer to three significant figures. volume of oxygen .................................................... dm³[3]
6. (e)(i)A fuel cell generates electricity when hydrogen and oxygen react on platinum electrodes. Name a process used in industry to produce hydrogen.[1]
7. (e)(ii)Some cars use a hydrogen–oxygen fuel cell instead of a petrol (gasoline) engine as a source of energy. Describe two advantages of a hydrogen–oxygen fuel cell compared with a petrol (gasoline) engine. 1. 2.[2]