Chemistry Past Questions And Answers
Consider the following reaction equation: SO42-(aq) + 2H+(aq) + ye- → SO42-(aq) + H2O(1). The value of y in the equation is
- A. 2
- A. 2 B. 3
- C. 4
- D. 6
(a)(i) List three properties of elements which increase generally across a period in the Periodic Table,
(ii) Give two differences between a chemical reaction and a nuclear reaction.
(b) Use the information provided in the table below to answer Questions (i) - (vii).
Atom of Element | P | Q | R | S | T |
Mass Number | 16 | 40 | 35 | 18 | 20 |
Atomic Number | 8 | 20 | 17 | 8 | 10 |
Which of the atoms in the table above:
(i) are isotopes of the same element?;
(ii) contains 18 neutrons?;
(iii) is chemically unreactive?;
(iv) readily forms an ion with two positive charges?
(v) attain an octet structure by accepting one electron?;
(vi) forms ionic bond with R?;
(vii) belongs to the s-block in the Periodic Table?
(c) Describe in outline how each of the following conversions can be carried out in the laboratory. Write appropriate equations for the reactions involved in each case
(i) CuCO\(_3\) to Cu
(ii) MgO to MgSO\(_4\).
View Discussion (0)WAEC 2000 THEORY(a) Giving different examples, mention one metal in each case which produces hydrogen on reacting with
(i) dilute mineral acid
(ii) cold water;
(iii) steam;
(iv) hot, concentrated alkali.
(b) In an experiment, excess 0.50 mol dm\(^{-3}\) HCI was added to 1Og of granulated zinc in a beaker. Other conditions remaining constant, state how the reaction rate would be affected in each case, if the experiment was repeated using:
(i) 1.0 mol dm\(^{-3}\) HCI;
(ii) 8.0g of granulated zinc;
(iii) 10g of zinc dust;
(iv) a higher volume of 0.50 mol dm HCI;
(v) a reaction vessel dipped in crushed ice;
(vi) equal volumes of water and 0.50 mol dm\(^3\) HCI.
(c) Aluminium is extracted from its ore by electrolysis.
(i) Name the ore from which the metal is extracted.
(ii) State the role of molten cryolite in the extraction.
(iii) Describe in outline how the ore is purified before electrolysis
(iv) Calculate the current in amperes required to produce 18.0g of aluminium in 1.50 hours. [Al = 27.0; F = 96500C]
(d) Give the reason why
(i) aluminium, which is a reactive metal, is resistant to corrosion.
(ii) metals are generally good reducing agents.
View Discussion (0)WAEC 2002 THEORYUse this following information to answer this question. Compound X was boiled with concentrated hydrochloric acid for a long time. One of the products was found to be a sugar. What type of reaction was involved between compound X and concentrated hydrochloric acid?
- A. Polymerization
- B. Fermentation
- C. Hydrolysis
- D. Neutralization
All the following will liberate a gas when reacted with dilute hydrochloric acid except
- A) sodium tetraoxosulphate (VI) salt
- B) Sodium trioxocarbonate (IV) salt
- C) Sodium sulphide
- D) Sodium trioxonitrate (V)
Which of the following would increase the rate of reaction of chips of a metal M as shown in the equation below? M(s) + 2HCI(aq) → MCI2(aq) + H2(g)
- A. Diluting the hydrochloric acid
- B. Adding some distilled water
- C. Decreasing the temperature
- D. Grinding the metal into powder
What is oxidized in the reaction represented by the following equation? 3CU + 8HNO3 → 3Cu(NO3)2+ 2NO + 4H2O
- A. Oxygen
- B. Hydrogen
- C. Nitrogen
- D. Copper
Amino acids are obtained from proteins by
- A. Hydrolysis
- B. Oxidation
- C. Polymerization
- D. Reduction
Proteins in acid solution undergo?
- A. Substitution
- B. Fermentation
- C. Hydrolysis
- D. Polymerisation
A concentrated solution containing H+, Cu2+ ,OH-and CI- was electrolysed using platiunm electrodes which of the ions will be discharged at the cathods?
- A. H+
- B. Cu2+
- C. OH-
- D. CI-