Give reasons to support each of the following statements.

1. The iron and steel of bridges, ships and pipelines are protected from rusting by joining to a reactive metal such as magnesium. (0 mk)
2. Briefly explain two processes which add carbon dioxide to the air. (0 mk)

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John and Asha were debating about the processes that are involved during simple distillation. What processes will you recommend to them?

The laboratory technician planned to conduct an experiment for the preparation of gas Y. The following set of apparatuses was used: Flat-bottomed flask, thistle funnel, delivery tube, wire gauze, tripod stand and gas jars. Also pieces of zinc metal and dilute hydrochloric acid were used. (a) Identify gas Y. (b) What apparatus is missing in the set provided? (c) Draw a well labeled diagram for the preparation of gas Y in the laboratory. (d) Write the word equation for the laboratory preparation of gas Y.

1. Identify gas Y. (1 mk)
2. What apparatus is missing in the set provided? (1 mk)
3. Draw a well labeled diagram for the preparation of gas Y in the laboratory. (1 mk)
4. Write the word equation for the laboratory preparation of gas Y. (1 mk)

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(b) (i) Write its structure if strontium has a mass number 87 and atomic number 38. (ii) How many neutrons does it have? (iii) How many protons does it have?

1. Write its structure if strontium has a mass number 87 and atomic number 38. (0 mk)
2. How many neutrons does it have? (0 mk)
3. State and interpret Dalton's postulate that matter is made up of tiny indivisible particles called atoms. With reason, support or refute this postulate. (4 mk)
4. How many protons does it have? (1 mk)
5. How many protons does it have? (0 mk)

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Suppose that you have been appointed by the Chemistry teacher to prepare a morning speech titled "Classification of fuels based on their efficiency." Elaborate how you would prepare your presentation basing on the following concepts: (a) Pyrometric effect of burning (b) Heat Value (c) Ignition Point (d) Velocity of burning (e) Affordability

1. Pyrometric effect of burning (2 mk)
2. Heat Value (2 mk)
3. Ignition Point (2 mk)
4. Velocity of burning (2 mk)
5. Affordability (2 mk)

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Identify four properties of the molecules in part (a).

1. Identify four properties of the molecules in part (a). (2 mk)
2. Chlorine (2 mk)
3. What type of bond exists in the molecules in part (a)? (1 mk)
4. Identify four properties of the molecules in part (a). (2 mk)
5. Ammonia (2 mk)
6. Carbon dioxide (2 mk)
7. Identify four properties of the molecules in part (a). (2 mk)
8. Identify four properties of the molecules in part (a). (2 mk)

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