The pOH of a solution of 0.25 mol dm-3 of hydrochloric acid is

• A. 12.40
• B. 13.40
• C. 14.40
• D. 14.60

river contaminated by alkali waste will have a pH of about.

• A. 1
• B. 3
• C. 5
• D. 9

1.1 g of CaCI2 dissolved in 50 cm3 of water caused a rise in temperature of3.4°C. The heat of reaction, ∆H for CaCI2 in kj per mole is? (Ca = 40, CI = 35.5, specific heat of water is 4.18 jk-1

• A. -71.1
• B. -4.18
• C. +71.1
• D. +111.0

Which of the following measures is not suitable for controlling water pollution?

• A. treating industrial effluent and domestic sewage before discharge into water
• B. Controlling the use of agrochemicals
• C. recycling industrial and agricultural wastes
• D. burning industrial and agricultural wastes before discharge into water ways

The carbon atoms of ethane are

• A) sp² hybridized
• B) sp³ hybridized
• C) sp²d hybridized
• D) sp hybridized

Which of the following alkanes has the highest boiling point?

• A. Pentane
• B. Ethane
• C. Propane
• D. Methane

Going down group II in the periodic table normally

• A. ionization energy increases
• B. melting point increases
• C. shielding effect decreases
• D. electronegativity increases

Consider the reaction A(s)+ 2B(g)→ 2C(aq) + D(g) What will be the effect of a decrease in pressure on the reaction?

• A) the equilibrium will shift
• B) rate of forward reaction will increase
• C) rate of backward reaction will increase
• D) rates of forward and backward reaction are not affected

(a)(i) List three observable changes that take place when a dilute solution of copper (II) chloride is electrolysed using platinum electrodes. Stage III

(ii) Calculate the quantity of electricity used during electrolysis when a current of 0.21 ampere flows for 2 hours.

(iii) State what is meant by the term preferential discharge of ions in electrolysis

(iv) Give one factor which influences the preferentia! discharge of ions during electrolysis.

(v) State one Q difference between-a conductor and an electrolyte.

(b) Consider the reaction represented by the equation below: Na\(_2\)S\(_2\)O\(_{3(aq)}\) + 2HCI\(_{(aq)}\) \(\to\) 2NaCI\(_{(aq)}\) + H\(_2\)O\(_{(l)}\) + SO\(_{2(g)}\) + S\(_{(s)}\)

(i) List two factors that can affect the rate of this reaction.

(i) Which of the products can be readily used to measure the rate of the reaction. Give a reason for your answer.

(iii) Name two instruments that can be used to measure factors in (b)(i) above.

(c)(i) State the reasons for regarding rusting and burning as oxidation processes.

(ii) I. Write the balanced half equations for the following redox reaction: Mg\(_{(s)}\) + Fe\(^{2+}_{(aq)}\) ----> Mg\(^{2+}_{(aq)}\) + Fe\(_{(s)}\)

II. Which of the reactants is the oxidizing agent?

Ill. State the change in the oxidation number of the oxidizing agent.

(d)(i) State one ore from which each of the following metals can be extracted. I. Tin II. Iron (ii) List two uses of copper (iii) Name one alloy of tin.

An example of a polysaccharides is?

• A. —dextrose
• B. mannose
• C. glucose
• D. starch