www.prep.ng: JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2015 (TEXT)

Thursday, 28 February 2019

JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2015 (TEXT)

jamb past questions and answers on chemistry 2015

1. Which of the following statements is correct?
A. The average kinetic enemy of a gas is directly proportional to its temperature
B. At constant temperature, the volume of a gas increases as the pressure increases
C. The pressure of a gas is inversely proportional to its volume
D. The temperature of gas is directly proportional to its volume

2.  Which are the correct IUPAC names for H – CO2CH3 and CH CH ?
A.  Methyl methanoate and ethene
B.  Metanoic acid and ethyne
C.  Ethyl methanoate and ethyne
D. Methyl methanoate and ethyne

3. A solution X on mixing with AgNO3 solution, gives a white precipitate soluble in NH3(aq). A solution Y, when added to X, also gives a white precipitate which is soluble on boiling. Solution Y contains __.
A.  Ag+ ion
B.  Pb2+ ion
C.  Pb4+ ion
D. Zn2+ ion

4.  Methane is a member of the homologous series called __.
A.  alkenes
B.  alcohols
C.  esters
D.  alkanes

5. Which of the following bonds exists in crystalline ammonium chloride (NH4CL)?
A.  ionic covalent
B.  ionic and co-ordinate
C.  ionic, covalent and co- ordinate
D.  covalent, co-ordinate and metallic

6.  Some copper (II) sulphate pentahydrate (CuSO4 5H2O), was heated at 120°C with the following results: Wt of crucible = 10.00 g; Wt of crucible + CuSO4.5H2O = 14.98g; Wt of crucible + residue = 13.54 g. How many molecules of water of crystallization were lost? [H= 1, Cu = 63.5, O =16, S = 32]
A.  1
B.  2
C.  3
D.  4


jamb past questions and answers on chemistry 2015

7.  Which of the curves shown above represents the relationships between the volume (v) and pressure (p) of an ideal gas at constant temperature?
A.  1
B.  2
C.  3
D.  4

8. 12.0g of a mixture of potassium carbonate and potassium chloride were dissolved in a 250cm3 standard flask. 25cm3 of this solution required 40.00cm3 of 0.1 M HCI for neutralization. What is the percentage by weight of = 16, C = 12)? K2CO3 in the mixture (K = 39, O = 16, C = 12)
A.  60
B.  72
C.  82
D.  92

9.  Which of the following groups of physical properties increases from left to right of the Periodic Table? 
1. Ionization energy 
2. Atomic radius 
3. Electro-negativity 
4. Electron affinity

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

10. An element Z, contained 90%Its relative atomic mass is __.
A.  16.0
B.  16.2
C.  17.0
D.  17.8

11. What are the possible oxidation numbers for an element if its atomic number is 17?
A.  -1 and 7
B.  -1 and 6
C.  -3 and 5
D. -2 and 6

12.   How many valence electrons are contained in the element represented by
A.  3
B.  5
C.  15
D. 31

13. 10.0 dm3 of air containing H2S as an impurity was passed through a solution of Pb(NO3)2 until all the H2S had reacted. The precipitate of PbS was found to weigh 5.02 g. According to the equation: Pb(NO3)2 + H2S PbS + 2HNO3 the percentage by volume of hydrogen sulphide in the air is
A.  50.2
B.  47.0
C.  4.70
D. 0.47

14. A quantity of air was passed through a weighed amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of __.
A.  nitrogen
B.  neon
C.  argon
D. oxygen

15.  Water for town supply is chlorinated to make it free from __.
A.  bad odour
B.  bacteria
C.  temporary hardness
D. permanent hardness

16.  4.0 g of sodium hydroxide in 250 cm3 of solution contains __.
A.  0.40 moles per dm3
B.  0.10 moles per dm3
C.  0.04 moles per dm3
D. 0.02 moles per dm3

17. A major effect of oil pollution in coastal waters is the __.
A.  destruction of marine life
B.  desalination of the water
C.  increase in the acidity of the water
D. detoxification of the water

18.  In general, an increase in temperature increases the solubility of a solute in water because __.
A.  more solute molecules collide with each other
B.  most solutes dissolve with the evolution of heat
C.  more solute molecules dissociate at higher temperatures
D. most solutes dissolve with absorption of heat

19. The relatively high boiling points of alkanols are due to __.
A.  ionic bonding
B.  aromatic character
C.  covalent bonding
D. hydrogen bonding

20. Given that 15.00 cm3 of H2SO4 was required to completely neutralize 25.00 cm3 of 0.125 mol dm3 NaOH, calculate the molar concentration of the acid solution
A.     0.925 mol dm3
B.  0.156 mol dm3
C.  0.104 mol dm3
D.     0.023 mol dm3

21. What volume of 0.1 mol dm3 solution of tetraoxosulphate (VI) acid would be needed to dissolve 2.86g of sodium trioxocarbonate (IV) decahydrate crystals?
A.     20cm3
B.  40cm3
C.  80cm3
D. 100cm3
[H = 1, C = 12, O = 16, S= 32, Na 23].

22. The solution with the lowest pH value is __.
A. 5 ml of  M/10 HCL
B.  10 ml of  M/10 HCL
C.   15ml of M/5 HCL
D. 20ml of M/8 HCL


23. In which order are the following salts sensitive to light?
A.  Agl > AgCl > AgBr
B.  AgCl> Agl > AgBr
C.  AgBr > AgCI > Agl
D. AgCI > AgBr > Agl

24.   A metal m displaces Zinc from Zinc chloride solution. This shows that __.
A.  M is more electronegative than Zinc
B.  Zinc is above hydrogen in the series
C.  M is more electropositive than zinc
D. electrons flow from zinc to m

25.   Steam changes the colour of anhydrous cobalt (II) chloride from
A.  blue to pink
B.   white to red
C.  white to green
D.  blue to white

26.  When at equilibrium, which of the reactions below will shift to the right if the pressure is increased and the temperature is kept constant?
A.  2SO3(g) === 2SO2(g) + O2(g)
B.  2CO2(g) === 2CO(g) + O2(g)
C.  2H2(g) + O2(g) === 2H2O(g)
D. 2NO(g) === N2(g) + O2(g)

27. 2CO(g) + O2(g) 2Co2(g)
Given that ΔH [CO] is -110.4 kJmol-1 and ΔH [CO2] is -393.0 kJmol-1, the energy change for the reaction above is  __.
A.  -503.7 kJ
B.  -282.6 kJ
C.  +282.6 kJ
D. +503.7 kJ

28. Which of these properties gives a solid its definite shape?
A.  Strong inter-molecular attraction
B.  High melting point
C.  High boiling point
D. Weak inter-molecular attraction

29. When a crystal was added to the clear solution of its salt, the crystal did not dissolve and the solution remained unchanged. This showed that the solution was  __.
A.  supersaturated
B.  concentrated
C.  unsaturated
D. saturated

30.  If the electron configuration of an element is 1s22s22p5, how many unpaired electrons are there?
A.  2
B.  5
C.  1
D. 4

31. The substance that is used in the steel industry for the removal of carbon, sulphur and phosphorus impurities from pig iron is  __.
A.  oxygen
B.  chlorine
C.  nitrogen
D. hydrogen

32. Hydrogen sulphide gas can act as  __.
A.  an oxidizing agent
B.  a dehydrating agent
C.  a bleaching agent
D. a precipitating agent

33. Which of the following is used as a rocket fuel?
A.  HNO3
B.  CH3COOH
C.  H2SO4
D. HCI
34. The bleaching action of chlorine is effective due to the presence of  __.
A.  Hydrogen chloride
B.  Water
C.  Air
D. Oxygen

35. Mineral acids are usually added to commercial hydrogen peroxide to  __.
A.  Oxidize it
B.  decompose it
C.  minimize its decomposition
D. reduce it to water and oxygen

36. Aluminium containers are frequently used to transport trioxonitrate (v) acid because aluminium
A.  has a low density
B.  does not react with the acid
C.  does not corrode
D. has a silvery - white appearance

37.  Ethyne is passed through a hot tube containing organo-nickel catalyst to produce  __.
A.  Isoprene
B.  polythene
C.  ethanol
D. benzene

38. The process of converting starch to ethanol is  __.
A.  cracking
B.  distillation
C.  fermentation
D. oxidation

39. An endothermic reaction is one during which heat is ____and can be represented by the symbol____. Which of the following combinations can be used accurately to complete the above definition?
A.  liberated -ΔH
B.  liberated +ΔH
C.  absorbed -ΔH
D. absorbed +ΔH

40.  Consider the following exothermic reaction 2SO2(g) + O2(g) = 2SO3(g). If the temperature of the reaction is reduced from 800C to 500°C, and no other change takes place, then  __.
A.  the reaction rate increases
B.  concentration of SO2 decreases
C.  concentration of SO2 increases
D. SO2 gas becomes unreactive

ANSWERS

1. A
2. D
3. B
4. D
5. C
6. D
7. C
8. D
9. C
10. B
11. A
12. B
13. C
14. D
15. B
16. A
17. C
18. C
19. D
20. C
21. D
22. D
23. D
24. C
25. A
26. C
27. B
28. A
29. D
30. C
31. A
32. D
33. A
34. B
35. C
36. B
37. D
38. C
39. D
40. C

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