A balanced chemical equation obeys the law of

• A) conservation of mass
• B) definite proportions
• C) multiple proportions
• D) conservation of energy

Which of the following substances is the anode in the dry Leclanche cell ?

• A. Carbon rod
• B. Muslin bag
• C. The seal
• D. Zinc container

(a)(i) List two properties of iron that are characteristic of transition metals

(ii) Using equations only, show the processes involved in the extraction of iron and the removal of impurities in the blast furnace.

(iii) The following reaction occurs when a piece of iron is exposed to moist air for some days:

4Fe\(_{(s)}\) + 3O\(_{2(g)}\) + xH\(_2\)O\(_{(l)}\) —> 2Fe\(_2\)O\(_3\)\(_{(s)}\) State three methods by which this reaction can be prevented

(iv) What is the oxidation number of iiron in the product in (iii) above?

(b)(i) Arrange the following metals in the order of increasing reactivity. Hence, state which of them is/are extracted by electrolysis Au, Zn, Mg, Na, Sn, Ca

(ii) Why is zinc said to be amphoteric?

(c)(i) Define oxidation in term of electron transfer

(ii) Determine how many moles of electrons are transferred when 4825 coulombs of electricity are passed through an electrolytic cell. [1F = 96500C]

(iii) Calculate the number of copper (II) ions that will be discharged by 0.250F. [Avogadro constant = 5.02 x 10\(^{23}\)

The type of isomerism exhibited by cis and trans isomers is?

• A. positional
• B. geometrical
• C. functional
• D. optical

Which of the following does not support the fact that air is a mixture?

• A) the constituents of air are in a fixed proportion by mass
• B) it cannot be represented with a chemical formula
• C) the constituents of air can be separated by physical by physical means
• D) none of the above

One method of driving the position of equilibrium of an endothermic reaction forward is to?

• A. increase temperature at constant pressure
• B. dcrease pressure at constant temperature
• C. cool down the apparatus with water
• D. decreases temperature at constant pressure

(a)(i) What is meant by the rate of a chemical reaction?

(ii) Explain in terms of the vision theory, the effect of temperature increase on reaction rate.

(b) When hydrogen peroxide is exposed to air, it decomposes

(i) Write an equation for the reaction.

(ii) Outline an experiment to illustrate that effect of a named catalyst on the rate of decomposition.

(iii) Sketch an energy profile diagram to show the effect of the catalyst on the reaction rate, given that the reaction is exothermic.

(c)(i) Explain why enthalpy data alone cannot be used to predict whether a reaction can occur spontaneously or not.

A hydrocarbon has an empirical formula CH and a vapour density of 39. Determine its molecular formula.[C = 12, H = 1]

• A) C2H6
• B) C3H8
• C) C3H4
• D) C6H6

Catalytic hydrogenation of alkenes produces compounds with the general formula

• A. C_nH_2n+1OH
• B. C_nH_2n+1
• C. C_nH_2n+2
• D. C_n2n-2

What is the atomic number of an element whose cation Y+ has the electronic configuration 1s₂2s₂2p₆

• A. 9
• B. 10
• C. 11
• D. 12