Question

(A) Write down two examples for each of the following substances: [3 Marks]
a) Food preservative b) Fuel c) Building material

(B) Answer the following questions: [3 Marks]
(1) From what materials are the following made?
(a) Mortar and pestle
(b) Test tube holder
(2) Why are most of the apparatus made of glass?

(C) Answer the following questions:
(i) State the function of asbestos fixed at the centre of wire gauze. [1 Mark]
(ii) What is the function of exhaust fans in a chemistry laboratory? [1 Mark]
(iii) What should we do in case of accidental contact with a dangerous chemical? [2 Marks]

Answer 1

(A) a) Food preservative: <Any 2> (Each example carries 0.5 marks)

• Common salt
• Sodium benzoate
• Sodium metabisulphate
• Salicylic acid

b) Fuel: <Any 2> (Each example carries 0.5 marks)

• Petrol
• Diesel
• Coal
• Cooking gas (L.P.G - Liquified petroleum Gas)

c) Building material: <Any 2> (Each example carries 0.5 marks)

• Glass
• Paints
• Mortar
• Steel

(B) (1) (a) Mortar and pestle is a container made of porcelain used to crush and grind solids. [0.5 Marks]
(b) Test tube holder is a metallic rod with a clamp at one end and a clamp at another. [0.5 Marks]

(2) Most lab apparatuses are made of glass because:
(a) glass is a transparent material, and we can see through it clearly. [0.5 Mark]
(b) glass can withstand high temperatures. [0.5 Mark]
(c) glass is easy to clean. [0.5 Mark]
(d) glass does not react with most of the chemicals used in experiments. [0.5 Mark]

(C) (i) On heating an apparatus on wire gauze, the asbestos fixed at the centre of the wire gauze initiates an even heat distribution at the bottom. It also prevents glass apparatus from cracking. [1 Mark]
(ii) Exhaust fans are fitted near the walls in a chemistry laboratory to expel poisonous gases and fumes to make the work area safe. [1 Mark]
(iii) In case of accidental contact with a dangerous chemical, we must immediately wash the affected area with running cold water. [1 Mark]
(iv) We must then report it to the teacher or lab instructors, who will help in first aid. We must also ensure that others have moved away from the accident area. [1 Mark]