The product of the reaction between ethanol and excess acidified K₂Cr₂O₂ is

• A. ethanal
• B. ethylethanoate
• C. ethanoic acid
• D. ethyne

State which of the following can exhibit geometric isomerism:

Give reason for your answer

When ammonium chloride is dissolved in water in a test tube, the tube feels colder showing that

• A. the solution is unsaturated
• B. sublimation has ocurred
• C. ammonia gas is evolved
• D. the process is endothermic

(a) State the phenomenon illustrated by the:

(i) spreading of the smell of hydrogen sulphide gas in the laboratory;

(ii) existence of atoms of the same element having different mass numbers

(b) The atomic number of an element is 17. It has different atoms containing 18 neutrons and 20 neutrons, with a relative abundance of 75% and 25% respectively. Calculate the relative atomic mass of the element.

Alkanes are used mainly

• A. in the production of plastics
• B. as domestic and industrial fuels
• C. in the textile industry
• D. in the hydrogenation of oils

Classify each of the following as physical change or a chemical change:

(a) fractional distillation of liquefied air;

(b) cracking of petroleum fractions;

(c) conversion of rhombic sulphur to monoclinic sulphur;

(d) chromatographic separation of chlorophyll.

Which of the following separation is routinely applied in the petroleum industry

• A. Filtration
• B. Chromatography
• C. Evaporation
• D. Fractional distillation

(a) State one air pollution that causes:

(i) blood poisoning

(ii) acid poisoning

(iii) blackening of the walls of buildings

(b) Mention one major chemical industry in each case which requires the following as raw materials:

(i) petrochemicals;

(ii) cellulose.

In which of the following pairs are both substances deliquescent?

• A. CaCI2 and H2SO4
• B. NaOH and MgSO4 7H2O
• C. CaCI2 and NaOH
• D. CUO and NaCI

(a)(i) List four characteristic properties of transition metals

(ii) Name two metals that can be extracted from their ore by electrolysis.

(b)(i) Determine the oxidation number of chromium in Cr\(_2\)O\(^{2-}_{7}\)

(ii) State the colour observed on adding a few drops of dilute tetraoxosulphate (VI) acid to the system representedby the following equation: Cr\(_2\)O\(^{2-}_{7(aq)}\) + H\(_2O_{(l)}\) \(\rightleftharpoons\) 2CrO\(^{2-}_{4(aq)}\) + 2H\(^+_{(aq)}\). Explain your answer.

(c)(i) State and explain what would be observed if hydrogen sulphide gas were bubbled into acidified K\(_2\)Cr\(_2\)O\(_7\). Write an equation for the reaction.

(ii) What precaution should be taken to avoid excessive exposure to hydrogen sulphide gas while it is being generated in the laboratory?