30 Chemistry Examination Questions and Answers

1.   Which of the following is a physical change?

A. The bubbling of chlorine into water

B. The bubbling of chlorine into a jar containing hydrogen

C. The dissolution of sodium chloride in water

D. The passing of steam over heated iron

2. In the reaction: SnO2 + 2C → Sn + 2CO, the mass of coke containing 80% carbon required to reduce 0.302 kg of pure tin oxide is [Sn –=119, O = 16, c = 12].

A. 0.40 kg     B. 0.20 kg      C. 0.06    D. 0.04 kg 

3. The Avogadro number of 24 g of magnesium is the same as that of 24 g of magnesium is the same as that of

A. 1g of hydrogen molecules B. 16 g of oxygen molecules

C. 32 g of oxygen molecules D. 35.5 g of chlorine molecules

4. The volume occupied by 1.58g of a gas at s.t.p is 500cm3. What is the relative molecular mass of the gas? [G.M.V at s.t.p = 22.40 dm3]

A. 28        B. 32        C. 44       D. 71

5. Which of the following terms indicates the number of bonds that can formed by an atom?

A. Oxidation number B. Valence

C. Atomic D. Electronegativity

6. Chlorine consisting of two isotopes of mass number 35 and 37, has an atomic mass of 35.5. The relative abundance of the isotope of mass number 37 is

A. 20         B. 25          C. 50          D. 75

7. Which of the following can be obtained by fractional distillation?

A. Nitrogen from liquid air                                          

B. Sodium chloride from sea water

C. Iodine from a solution of iodine in carbon tetrachloride

D. Sulphur from a solution of Sulphur in carbon disulphide

8. An iron ore is known to contain 70.0% Fe2O3. The mass of iron metal which can be theoretically be obtained from 80 kg of the ore is [Fe = 56, O = 16]

A. 35.0 kg         B.39.2kg          C.70.0kg      D. 78.4kg

9. Which of the following alcohols would have the lowest boiling point?                                                           

A. Butanol       B. 2-Methyl,butanol                          C. Propanol     D. Ethanol

10. What type of alcohol is 2-methyl-2-pentanol?                 A. Primary                                  B. Secondary            C. Tertiary                                  D. Quaternary

11. The 100% rating of petrol is referenced to        A. n-Octane                B. Isopropyl,butane                  C. 2-methyl,buta-1,3-diene     D. 2,2,4-trimethyl,pentane .

12. Select the incorrect statement regarding terminal alkynes.                                                                          

A. Methylacetylene is an example of terminal alkynes                                                                            B. Terminal alkynes are more acidic when compared with alkenes   

C. Terminal alkynes are not as acidic as alkanes    D. These have a replaceable acidic hydrogen atom 

13. The IUPAC nomenclature for the following compound is —- CH3CH2CH2CH2C(CH3)(CH2CH2CH3)CH2CH3                                                                                      

A. 5-methyl-5-ethyloctane  

B. 5-methyl-5-propylheptane                                      C. 4-ethyl-4-methyloctane     

D.  3-ethyl-3-methyloctane 

14. The standard enthalpies of formation of CO2(g), H2O(g) and CO(g) in kJ mol-1 are -394, -242 and -110 respectively. What is the standard enthalpy change for the reaction CO(g) + H2O(g) →CO2(g) + H2(g)?                                                              

 A. -42 KJ mol-1                     B. +42 KJ mol-1               C. -262 KJ mol-1                    D. +262 KJ mol-1

15. Calculate the solubility in mol dm-3 of 40g of CuSO4 dissolved in 100cm3 of water at 120oC.       [Cu = 64, S = 32, O = 16]              

A. 4.00       B. 2.50         C. 0.40              D. 0.25

16.  If the solubility of a salt sample at 60°C is 0.20 mol/dm3 and 0.08 mol/dm3 at 25°C, what mass of 300cm3 of the salt salt solution will crystallize out upon cooling from 60°C to 25°C? [Given than the molar mass of the salt is 101 g/mol] 

A. 3.64g  B. 36.36g    C. 6.06g     D. 2.42g

17.  The reaction between hydrogen and iodine may be represented by the equation H2(g)+ I2(g) → 2HI(g), and is exothermic. Therefore                                                                      

A. an increase in temperature favours the forward reaction                                                          B. an increase in pressure favours the backward reaction                                                                        C. both pressure and temperature must be increased to favour the forward reaction                D. a decrease in temperature will favour the forward reaction

18.   A piece of radioactive material contains 64 atoms. If the half life of the material is 4 seconds, the number of disintegration in the 20th second is___                                                                          

A. 2 atoms  B. 4 atoms     C. 16 atoms      D. 32 atoms

19.  In two separate experiments, 0.36g and 0.71g of chlorine combined with a metal X to give Y and Z respectively. An analysis showed that Y and Z contain 0.20 g and 0.40 g of X respectively. The data above represents the law of

A. multiple proportion      B. conservation of mass   C. Constant composition   D. reciprocal proportion

20. Calculate the volume of carbon (IV) oxide measured at s.t.p produced when 1kg hydrogen trioxocarbonate (IV) is totally decomposed by heat [G.M.V at s.t.p = 22.4 dm3, K=39, O = 16, C = 12, H = 1]                                                                          

A. 28 dm3 B. 56 dm3 C. 112 dm3  D.196 dm3

21. Atoms of element X (with 2 electrons in the outer shell). Which of the following statements is FALSE? The compound formed

A. has formula XY B. is likely to be ionic

C. contains X2+ ions D. contains Y- ions. 

22. The ions X- and Y+ are isolectronic, each protons are in the nuclei of the neutral atoms of X and Y respectively?

A. 10 and 10       B. 9 and 9      C. 11 and 9 D. 9 and 11

23. The electronic configuration of an element is 1s22s22p6 3523p3. How many unpaired electrons are there in the element?  

A. 5  B. 4   C. 3   D. 2

24. Which of the following represents the type of bonding present in ammonium chloride molecule?

A. ionic only                          B. Covalent only

C. ionic and dative covalent     D. Dative covalent only

25. wH2SO4 + xAI(OH)_3 → zAI2 (SO4)3. The respective values of w,x,y and z in the equation above are

A. 2,2,5 and 1 B. 3,2,5 and 2

C. 3,2,6 and 1 D. 2,2,6 and 2

1. C   16. A

2. C   17. D

3. C   18. A

4. D   19. D

5. B    20. C

6. B    21. N.A

7. A    22. D

8. D    23. C

9. D    24. N/A

10. C   25. N/A 

11. D    26. C

12. C     27. B

13. D     28. D

14. A     29. A

15. B     30. B