In an experiment to determine the structure of an atom, Rutherford bombarded positively charged alpha particles to the atoms of a gold foil and observed the following: (a) Most of the alpha particles passed through the gold foil without suffering any deflection. (b) Very few particles rebounded completely on hitting the gold, foil. What is the interpretation of each of the observations?

1. Interpretation of most alpha particles passing through the gold foil without deflection. (0 mk)
2. Interpretation of very few particles rebounding completely on hitting the gold foil. (0 mk)

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Write the order of reaction with respect to Br and H , together with overall order of reaction in rate equation: R=k[Br ] [H ] .

1. What is the order of reaction with respect to H₂? (0 mk)
2. Overall order of reaction. (0 mk)
3. What is the overall order of reaction? (0 mk)

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(a) A chemistry teacher instructed his students to dissolve exactly 20 g of sodium hydroxide (NaOH) pellets in one dm3 of solution. Name and explain such kind of a solution. (b) What is the molarity of a solution that has 0.491 g of NaOH dissolved in 400 cm3 of solution?

1. Name and explanation of the solution prepared by dissolving exactly 20 g of NaOH in 1 dm3. (0 mk)
2. Molarity of a solution with 0.491 g of NaOH in 400 cm3. (0 mk)

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Derive the degree of dissociation of weak acid. Given that is an equation for the dissociation of a weak acid electrolyte, show that the degree of dissociation    is given by  . Ka c

1. Derive the expression for the degree of dissociation (α) for a weak acid HA ⇌ H⁺ + A⁻. (0 mk)
2. Derivation of the degree of dissociation of a weak acid. (0 mk)

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Briefly explain why ammonia molecule readily coordinate with cation of the transition metals but ammonium ion (NH4+ ) does not.

(a) Complete the reactions in which: (i) methyl benzene reacted with bromine under FeBr , (ii) methyl benzene reacted with bromine under UV-light. (b) Account for the formation of products in part (a).

1. Reaction of methyl benzene with bromine under UV-light. (0 mk)
2. Account for the formation of products in part (a). (0 mk)

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Give six activities on how to prepare a lesson by using an inquiry based learning approach to teach the topic of acids and bases.

1. Activity 6 (0 mk)

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Account for the use of methyl orange indicator during titration of HCl against Na CO , and the use of phenolphthalein indicator in titration of HCl against NaOH.

1. Use of phenolphthalein in titration of HCl against NaOH. (0 mk)

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Give three factors to consider when preparing a chemistry lesson for Form One class.

1. Factor 3 (0 mk)

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Study the reaction for benzene against electrophile-nucleophile molecule with symbol E-NU under catalyst to form benzene substituted with E together with molecule H-NU.

1. Describe the mechanism of the reaction. (0 mk)

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Calculate standard heat of formation of propane given that the heat of combustion of propane (C H ) is -2220.2 kJmol-1 and the heat of formation of carbon dioxide (CO ) and that of water (H O) as -393 kJmol-1 and -285 kJmol-1 respectively.

1. Calculate the standard heat of formation of propane. (0 mk)

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Illustrate with four points, the causes of soil pH in the garden soil which has been tested and found to have a pH value of 4.10.

1. Cause 4 (0 mk)

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Give the importance of analyzing chemistry syllabus before the commencement of teaching in five points.

1. Importance 5 (0 mk)

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Analyze five points on the significance of keeping records of continuous assessment.

1. Significance 5 (0 mk)

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