chemistry Past Questions And Answers

2491

(a)(i) Explain briefly the term chemical industry.

(ii) State three factors that should be considered in siting a chemical industry.

(b)(i) Describe briefly twin is extracted from its ore.

(ii) Give two uses of tin.

(c)(i) Name the constituents of cement.

(ii) How does mortar set?

(d)(i) Explain briefly the term pollution.

(ii) Give two examples of air pollutants.

(e) Consider the following reversible reaction which occurred at the temperature of 298K:

N\(_{2(g)}\) + 3H\(_{2(g)}\) \(\rightleftharpoons\) 2NH\(_{3(g)}\); \(\bigtriangleup\)H = —92.37kJ

Explanation

(a)(i) Explain briefly the term chemical industry: It is an industry which uses chemical processes convert raw materials into useful products.

(ii) State 3 factors that should be considered in sitin chemical industry. (1) Availability of resources needed. (2) Good communication skills. (3) Nearn to markets. (4) Availability of labour. (5) Availability of space. (6) Good climate condition. (7) Favourable transport system (8) Nearness to source of energy. (9) Nearness to raw materials (10) Government policy.

(b)(i) Describe how tin is extracted from its ore: The ore is crushed into powder, washed with water and filtered to remove impurities/concentration of ore. The ore is roasted in air to remove impurities. roasted is mixed with coke/charcoal and heated in a furnace/high temperature/1300°C where it is reduced to tin/C + SnO\(_2\) ---> Sn + O\(_2\). Limestone is added to remove earthly impurities as slag/CaCO\(_2\) + SiO\(_3\) ---> CaSiO\(_3\) + CO\(_2\) Molten tin is tapped off.

(ii) It is used to coat iron or steel (as a protection aga corrosion). It is used in making alloys (e.g. Bronze, type metal, solder).

(c)(i) Name the constituents of cement: Calcium oxide/Calcium trioxocarbonate(IV), Silicon(IV) oxide and Aluminium oxide.

(ii) How does mortar set? Mortor is a mixture of sand, cements/lime and WE When mortar is placed between two blocks it absorbs CO\(_2\) from the atmosphere to form CaCO\(_3\) with m given out.

(d)(i).Explain briefly the term pollution: Pollution – introduction of harmful substance the environment/contamination of environment.

(ii) Give two examples of air pollutants: Gases hydrocarbon, e.g. methane (CH\(_4\)), CO, NO\(_2\), SO\(_2\), NO, CFC's, oxides of lead, particuate matter, e.g. d pollen grains, soot, smoke and smog.

(e)(i) Consider the following reversible reaction wh occurred at the temperature of 298k:

N\(_{2(g)}\) + 3H\(_{2(g)}\) \(\rightleftharpoons\) 2NH\(_{3(g)}\); \(\Delta\)H = –92.37KJ.

List two factors that would increase the yield of NH\(_{3(g)}\) — (1) Increase in pressure of the system/decrease in volume of system.

(2) Decrease in temperature of tho system.

(3) Removal of ammonia/products.

View Discussion (0)WAEC 2013 THEORY

2492

Which of the following standard conditions is not correct about energy changes?

A. Standard temperature is 298K
B. B. Standard pressure is 1 atm
C. Concentration of solution must be 1 mol/dm³
D. ΔH at 298 K is the activation energy

View Discussion (0)WAEC 2020 OBJ

2493

The minimum volume of oxygen required for the complete combustion of a mixture of 10cm³ ?of CO and 15cm³ of H₂ ?is

A) 25.0cm³
B) 12.5cm³
C) 10.0cm³
D) 5.0cm³

View Discussion (0)POST UTME FUTO

2494

Which of the following statements is NOT a chemical property of an acid?

A. Evolution of ammonia when heated with ammonium salts
B. Evolution of carbon dioxide gas when added to a trioxocarbonate (IV) salt
C. Formation of salt and water with alkalis
D. Formation of salt and hydrogen gas with reactive metals

View Discussion (0)WAEC 2017 OBJ

2495

The compound formed between₁₄X and₁₆Y is?

A. XY
B. XY₂
C. X₂Y
D. X₄Y₆

View Discussion (0)WAEC 2015 OBJ

2496

Locally produced soap in which wood ash is used as the base is usually soft because the wood ash contains a lot of

A. sodium ions
B. potassium ions
C. lithium ions
D. calcium ions

View Discussion (0)WAEC 1989 OBJ

2497

Which of the following statements is true of an endothermic reaction? I. Heat is absorbed from the surrounding II. The heat content of the products is more than that of the reactants III. The enthalpy change is positive IV. The surrounding is at a lower temperature than the system.

A. l only
B. l and ll only
C. l,ll and lll only
D. l, ll, lll and lV

View Discussion (0)WAEC 2004 OBJ

2498

Which trace gas in the atmosphere plays a significant role in the greenhouse effect?

A. Oxygen
B. Argon
C. Carbon dioxide
D. Nitrogen

View Discussion (0)JAMB 2023

2499

A trihydric alkanol is

A. Glycerol
B. Phenol
C. Glycol
D. Ethanol

View Discussion (0)JAMB 2001

2500

During the electrolysis of a salt of a metal M, a current of 0.5 A flows from for 32 minutes 10 seconds and deposits 0.325 g of M, What is the charge of the metal ion? (M = 65, If = 96,500 C per mole of electron)

A. 1
B. 2
C. 3
D. 4

View Discussion (0)JAMB 1993