Chemistry Past Questions And Answers
How many moles HCL will be required to react with potassium heptaoxodichromate (VI) to produce 3 moles of chlorine?
- A. 14
- B. 12
- C. 11
- D. 10
The oxidizing agent in the reaction, 3Br\(_2\) + 6OH\(^-\) \(\rightarrow\) BrO\(_3^-\) + 5Br\(^-\) + 3H\(_2\)O is _______
- A)Br\(_2\)
- B)OH\(^-\)
- C)BrO\(_3^-\)
- D)e\(^-\)
Bubbling excess carbon (IV) oxide into calcium hydroxide solution results in the formaton of
- A. CaO
- B. Ca(HCO3)2
- C. H2CO3
- D. CaCO3
Zn (s) + CuSO 4(aq) → ZnSO 4(aq) + Cu (s) In the reaction above, the oxidation number of the reducing agent changes from
- A) 0 to + 4
- B) 0 to + 2
- C) + 1 to + 2
- D) + 1 to + 3
(a) State (i) Pauli's Excusion principle;
(ii) Hund's rule of maximum multiplicity.
(b)(i) Write the electronic configuration of each of the following ions of copper: I. Cu\(_+\) II. Cu\(_{(2+)}\) [\(_{29}Cu\)]
(ii) Give the number of unpaired-electrons in each of the ions in (b)(i) above.
(iii) State the type of reaction represented by the following equation:
2Cu\(^+_{(aq)}\) \(\to\) Cu\(^{2+}_{(aq)}\) + Cu\(_{(s)}\)
(iv) Write the formula of one compound of Cu+.
(c)(i) Name the type of radiation that will I. penetrate lead block; II. be stopped by thin paper
(ii) Give the charge on each of the radiations mentioned in I(c)(i) above.
(iii) What term is used to describe each of the following nuclear processes?
I. Combination of two lighter nuclei to form a heavy nucleus II. Splitting of a heavy nucleus into two or more lighter nuclei
III. Time required for one-half of the atoms of a radioactive substance to decay.
(d) Arrange the following ions in order of increasing size. Give a reason for your answer in each case. I. Li\(^{+}\), K\(^{+}\), Na\(^{+}\); II. O\(^{2-}\), F\(^{-}\), N\(^{3-}\)
(e) Determine the percentage composition of phosphorus and oxygen in phosphorus (V) oxide [ P = 31, O = 16 ]
View Discussion (0)WAEC 2008 THEORYTwo solutions containing Pb2+ and AI3+ respectively can be distingusihed using
- A. NaOH(aq)
- B. NH3(aq)
- C. conc. HCI3
- D. conc. HCI
The following factors affect the solubility of a solid in a given solvent except
- A. nature of solute
- B. nature of solvent
- C. pressure
- D. temperature
On heating, the following trioxocarbonate (IV) salts decompose to give solid residue except
- A. ammonium trioxocarbonate (IV)
- B. calcium trioxocarbonate (IV)
- C. lead (ll) trioxocarbonate(IV)
- D. zinc trioxocarbonate (IV)
Which of the following on burning in air contributes to acid rain?
- A. Sulphur
- B. Magnesium
- C. Aluminium
- D. Zinc
(a)(i) State one physical method and one chemical method in each case by which the following can be removed:
I. Permanent hardness in water
II. A suspension of CaCO\(_3\) in water.
(ii) Give one disadvantage of hard water.
(b) Explain the following observations: (i) Crystals of washing soda become powdery on exposure to air for a long time
(ii) The concentration of chloride ions in 0.02 mol dm\(^{-3}\) calcium chloride solution is not the same s in 0.02 mol dm\(^{-3}\) sodium chloride solution.
(iii) Iron filings corrode faster than iron nails of the same mass.
(c)(i) Classify each of the following oxides as acidic, basic, neutral or amphoteric. I. ZnO II. CO III. NO\(_2\)
(ii) Give the formula of the acid anhydride of each of the following: I. H\(_2\)CO\(_3\) II. H\(_2\)SO\(_4\)
(iii) Give the IUPAC name of the following salts: I. COCl\(_2\) II. Mg(NO\(_3\))\(_2\).
(d)(i) Mention one pollutant associated with depletion of ozone layer in the atmosphere
(ii) Calculate the volume occupied by 0.125 mole of oxygen at 27°C and a pressure of 2.02 x 105 Nm\(^{-2}\) [I mole of gas occupies 22.4 dm\(^3\) at s.t.p; standard pressure = 1.01 x 105 Nm\(^{-2}\)]
(iii) State one process used for the industrial preparation of oxygen.
View Discussion (0)WAEC 2004 THEORY