Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
Your School's Whatsapp Group - Join Us now

Chemistry WAEC Past Questions

Clear Selections
Change Subject Post a Question Check Syllabus Study My Bookmarks Past Questions Videos Watch Video Lessons Download App

Post UTME Past Questions Agent
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
1296

(a) Define each of the following terms:

(i) ion; (ii) isotopes.

 

(b)(i) Consider the:element \(_{12}\)Mg and \(_{3}\)Al

I. Write the electron configuration of each element. II. Explain briefly why the first ionization energy of \(_{12}\)Mg is greater than that of \(_{13}\)Al.

(ii) Write the formulae of three different oxides of period 3 elements that react with water.

 

(c)(i) What are allotropes?

(ii) Name the two crystalline allotropes of carbon.

(iii) Give one industrial use of each allotrope named in (c)(ii).

 

(d) On warming crystals of sodium chloride with concentrated tetraoxosulphate (VI) acid, a gas was evolved.

(i) List two physical properties of the gas produced.

(ii) Write a balanced equation for the reaction.

 

(e) A certain chip W used in a circuit of a microcomputer has a mass of 5.68mg. Calculate the amount of W in the microcomputer. [ W = 28 gmol\(^{-1}\) ].

View Answer & Discuss WAEC 2014
1297

(a)(i) Outline the steps involved in the purification of water for town supply.

(ii) Give two cations that can cause hardness in water.

(iii) State two disadvantages of hardness of water.

(iv) List two sources of water pollution.

 

(b)(i) Explain briefly why water is a good solvent for sodium chloride but not for oil.

(ii) State the function of H\(_2\)SO\(_4\) in each of the following reaction equations:

(i) C\(_2\)H\(_5\)OH\(_{(l)}\) \(\to\)  C\(_2\)H\(_{4(g)}\)

(ii) MgO\(_{(s)}\) + H\(_2\)SO\(_4\)\(_{(aq)}\) —> MgSO\(_{4(aq)}\) + H\(_2\)O\(_{(l)}\)

(iii) C\(_{(s)}\) + conc. H\(_2\)SO\(_4\) --> CO\(_{(g)}\) + SO\(_{2(g)}\) + H\(_2\)O\(_{(l)}\)

 

(c) (i) Give the two products formed when chlorine water is exposed to sunlight.

(ii) I. Which of the compounds is suitable for the preparation of standard alkaline solution?

II. Give a reason for your answer in (c)(ii)I

View Answer & Discuss WAEC 2014
1298

(a)(i) Explain briefly each of the following terms: I. anode; II. cathode.

(ii) Sodium and aluminium are extracted by the electrolysis of molten sodium chloride and alumina respectively. Write balanced equations for the reactions at the anode and cathode during the extraction of: I. sodium; II. aluminium.

(iii) Explain briefly why extraction of aluminium is considered environmentally friendly while that of sodium is not.

 

(b) Consider the reaction represented by the following equation:

K\(_2\)Cr\(_2\)O\(_7\) + HC1--> KCI + CrCl\(_3\) + H\(_2\)O + Cl\(_2\)

(i) Explain briefly why this reaction is redox.

(ii) Write balanced half equations for the reaction.

(iii) Write the over-all balanced reaction equation.

 

(c) During the electrolysis of molten Al\(_2\)O\(_3\), a current of 6A was passed through the electrolyte for 1 hr. 30 mins. Calculate the mass of aluminium deposited at the cathode.

View Answer & Discuss WAEC 2014
Post UTME Past Questions Agent
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
1299

(a)(i) Define the term functional group.

 

(ii) Name the functional groups present in the following compound:

(b) Consider the following structure of an organic compound, Q.



(1) Name compound Q.

(ii) Write the balanced equation for the complete combustion of compound Q.

(iii) What type of reaction will compound Q undergo with chlorine?

(vi) Draw the structure of-the alkene that is an isomer of compound Q.

 

(c) A chemistry student was provided with four samples of organic compounds, A, B, C, and D. Samples A and B each decolourized bromine in tetrachloromethane but only sample B reacted with a solution of ammoniacal silver trioxonitrate (V) to give a white precipitate. Sample D reacted with sodium trioxocarbonate (IV) to liberate carbon (IV) oxide. When heat was applied to the mixture of samples C and D in a test tube and drops of concentrated tetraoxosulphate (VI) acid added, a product with a fruity odour was formed.

(i) Name the family of organic compounds to which samples A, B, C, and D belong.

(ii) State why samples A and B reacted with bromine in tetrachloromethane.

(iii) State the reason why sample B gave a white precipitate with the solution of ammoniacal silver trioxocarbonate (V).

(iv) Give the name o f the reactions between' samples C and D.

(v) State the two roles of the concentrated tetraoxosulphate (VI) acid in the reaction in (a)(iv).

 

(d) (i) Describe briefly the production of biogas using a biogas generator.

(ii) State two uses of biogas.

View Answer & Discuss WAEC 2014
1300

(a)(i) What is the common name given to the group VII elements?

(ii) Name the hydrides of the first two elements in group VII.

(iii) State three chemical properties of group VII elements.

(b) Copy and complete the following table:

Particles

Number

of Neutrons

Number

of electrons

Number

of prontons

Mass Number
W\(^{2+}\) 12     24
X\(^{2+}\)     8 16
Y   13   27
Z 12 11    

 

(c)(i) Define each of the followinc processes: I. nuclear fission; II. nuclear fusion.

(ii) Give one use of each process in (c)(i).

(d)(i) List three types of radiation that are produced during radioactivity.

(ii) Arrange the radiations listed in

(d)(i) in order of increasing: I. penetrating power; II. ionizing power.

View Answer & Discuss (1) WAEC 2013
Start a Free Practice Test
 
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Your School's Whatsapp Group - Join Us now
Post UTME Past Questions Agent
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts