The following are s-block elements except

• A. lithium
• B. magnesium
• C. potassium
• E. aluminium

When CuSO4_(aq) is added to Pb(NO₃)_2(aq)--------

• A. there would be no visible change
• B. a blue precipitate would be formed
• C. the resulting solution would become colourless
• D. a white precipitate would be formed

A mixture of 0.20 mole of Ar, 0.20 mole of N2 and 0.30 mole of He exerts a total pressure of 2.1 atm. The partial pressure of He in the mixture is?

• A. 0.90 atm
• B. 0.80 atm
• C. 0.70 atm
• D. 0.60 atm

A student prepares 0.5 M solution each of hydrochloric and ethanoic acids and then measured pH. The result would show that the?

• A. pH values are equal
• B. HCI solution has a higher pH
• C. sum of the values is 14
• D. ethanoic acid solution has a higher pH

An organic compound contains 60% carbon, 13.3% hydrogen and 26.7% oxygen. Calculate the empirical formula rn(C=12,H =1, O=16)

• A) C 5H 12O
• B) C 3H 8O
• C) C 6H 13O 2
• D) C 4H 9O

Which of the following methods can be used to separate a mixture of two miscible liquids with different boiling points?

• A. Decantation
• B. Distillation
• C. Evaporation
• D. Filtration

What volume of oxygen measured at s.t.p would be liberated on electrolysis by 9650 coulombs of electricity? (Molar volume of gas = 22.4 dm³, F = 96,500 C mol-)

• A. 22.4 dm³
• B. 11.2 dm³
• C. 1.12 dm³
• D. 0.560 dm³

(a) Draw an energy profile diagram to illustrate a catalysed exothermic reaction and label parts of the curves representing the following:

(i) activated complex (without catalyst);

(ii) activated energy (with catalyst)

(iii) enthalpy change

(b) Give the reasons for the following observations:

(i) A balloon filled with liyilrogen becomes deflated faster than a balloon filled with air under the same conditions.

(ii) Hydrogen peroxide decomposes slowly at room temperature but when a pinch of MnO, is added, bubbles form rapidly.

(iii) A solution of hydrogen chloride as in methylbenzene has no effect on `litmus but a solution of the gas in water turns blue litmus paper red.

(c) Consider the reaction represented by the following equation: 2MnO\(^-_{4(aq)}\) + 5C\(_2\)O\(^{2-}_4\) + 16H\(^+\) \(\to\) 2Mn\(^{2+}_{(aq)}\) + 8H\(_2\)O\(_{(l)}\) + 10C\(_{2(g)}\) .

Write down: (i) the species undergoing reduction giving reasons;

(ii) the reducing agent giving reasons;

(iii) the reduction half equation;

(iv) one observation made during the reaction.

(d)(i) What is an electrochemical cell?

(ii) State three differences between an electrochemical cell and an electrolytic cell.

An organic compound contains 69% carbon, 15.3% hydrogen and 30.7% oxygen. Calculate the the empirical formula [C=12, H = 1, O = 16]

• A. C\(_4\)H\(_12\)O
• B. C\(_3\)H\(_9\)O
• C. C\(_4\)H\(_9\)O
• D. C\(_3\)H\(_8\)O

The change in the oxidation state of iron in the reaction represented by the equation: 2FeCl3+H2S→2FeCl2+2HCl+S is

• A. +2 to +3
• B. 0 to +2
• C. +3 to +2
• D. +3 to 0