Thursday, 28 February 2019


jamb past questions and answers on chemistry 2017
1.   The flame used by welders in cutting metals is __.
A.   butane has flame
B.   acetylene flame
C.   Kerosene flame
D.   Oxy-acetylene flame
jamb past questions and answers on chemistry 2017

2.   At room temperature (300k) in fig 1
A.   Y is twice as soluble as X.
B.   X is twice as soluble as y
C.   X and Y are soluble to the same extent
D.   X is three times as soluble as Y

3.  Tetraoxosulphate(vi)acid is prepared using the chemical reaction SO3(g) + H2O(s) H2SO4(l). Given the heats of formation for SO3(g), H2O(l) and H2SO4(l) as -395KJmol-1, -286KJmol-1 and –811KJmol-1 respectively, the enthalpy change accompanying this reaction is __.
A.   -1032KJ
B.   -130KJ
C.   +130KJ
D.   +1032KJ

 4.   In two separate experiments 0.36g and 0.71g of chlorine combined with a metal X to give Y and Z, an analysis showed that Y and Z contain 0.20g and 0.40g of X respectively. The data above represents the law of __.
A.   multiple proportion
B.   conservation of mass
C.   constant composition
D.   reciprocal proportion

5.   If an element x of atomic number z and mass number y is irradiated by an intense concentration of neutrons, the relevant nuclear equation is __.jamb past questions and answers on chemistry 2017

6.   The vapour density of a gas may be defined as __.
A.   the mass of a unit volume of the gas compared to an equal volume of water vapour
B.   the mass of a unit volume of the gas compared to an equal volume of hydrogen
C.   the mass of a unit volume of the gas compared to an equal volume of oxygen
D.   The mass of a unit volume of the gas minus the vapour pressure of water

7.   30cm3 of oxygen at 10 atmosphere pressure is placed in a 20dm3 container. Calculate the new pressure if temperature is kept constant.
A.   6.7 atm
B.   15.0 atm
C.   60.0 atm
D.   66.0 atm

8.   A liquid begins to boil when __.
A.   its vapour pressure is equal to the vapour pressure of its solid at the given temperature
B.   molecules start escaping its surface
C.   its vapour pressure equals the atmospheric pressure
D.   its volume is slightly increased

9.   Four elements W, X, Y and Z have atomic numbers 2, 6, 16 and 20 respectively. Which of these elements is a metal?
A.   X
B.   W
C.   Z
D.   Y

10. When cathode rays are deflected unto the electrode of an electrometer, the instrument becomes __.
A.   negatively charged
B.   positively charged
C.   neutral
D.   bipolar

11.When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as __.
A.   disintegration
B.   polymerization
C.   cracking
D.   degradation

12.If concentrated sulphuric acid is added to sugar and warmed gently, the sugar changes from white to brown and finally to a black mass of carbon. In this reaction, concentrated sulphuric acid is acting as __.
A.   a drying agent
B.   an oxidizing agent
C.   a dehydrating agent
D.   a reducing agent

13.Smoke consists of __.
A.   solid particles dispersed in liquid
B.   solid or liquid particles dispersed in gas
C.   gas or liquid particles dispersed in liquid
D.   Liquid particles dispersed in liquid.

14.In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:
jamb past questions and answers on chemistry 2017
15. P(g) + Q(g)  3R(s) + S(g) ∆H is negative. Which of the following will increase the yield of R?
A.   using a larger closed vessel?
B.   increasing the temperature.
C.   Removing some S
D.   Adding a positive catalyst

16.The mass of silver deposited when a current of 10A passed through a solution of silver salt for 4830s is __.
A.   108.0g
B.   54. 0g
C.   27.0g
D.   13.5g

17.CO(g) + H2O(g) CO2(g) + H2(g) from the reaction above, calculate the standard heat change if the standard enthalpies of formation of CO2(g), H2O(g) and CO2(g) in KJmol-1 are -394, -242 and -110 respectively.
A.   -282KJmol-1
B.   -42KJmol-1
C.   +42KJmol-1
D.   +262KJmol-1

18.If the electron configuration of an element is 1S22S22p5, how many unpaired electrons are there?
A.   2
B.   5
C.   1
D.   4

19.Which of the following gases can best be used for demonstrating the fountain experiment? 
(i) Nitrogen 
(ii) Ammonia 
(iii) Nitrogen(i)oxide 
(iv) Hydrogen chloride
A.   (ii) and (iii)
B.   (i) and (iii)
C.   (ii) and (iv)
D.   (ii) only

20.The coloured nature of transition metal ions are associated with their partially filled __.
A.   f-orbital
B.   S-orbital
C.   P-orbital
D.   d-orbital

21.Which of the following separation processes is most likely to yield high quality ethanol (≥ 95%) from palm wine?
A.   fractional distillation without a dehydrant
B.   simple distillation with a dehydrant
C.   fractional distillation with a dehydrant
D.   column chromatography

22.The products formed on hydrolysis of
jamb past questions and answers on chemistry 2017

 23. In the reaction: 3CuO + 2NH3 3Cu +3H2O + N2 how many electrons are transferred for each mole of copper produced?
A.   4.0 x 10-23
B.   3.0 x 10-23
C.   1.2 x 1024
D.  6.0 x 1024

24.   The electronic configuration of an element is 1s22s22p63S23p63. How many unpaired electrons are there in the element?
A.   5
B.   4
C.   3
D.   2

25.  8.0 g of an element X reacted with an excess of copper (II) tetraoxosulphate (VI) solution to deposit 21.3g of copper. The correct equation for the reaction is __.
A.  X(s) + CuSO4(aq) Cu(s) + XSO4(aq)
B.  X(s) + 2CuSO4(aq) 2Cu(s) + X(SO4)2(aq)
C.  2X(s) + CuSO4(aq) Cu(s) + X2SO4(aq)
D.   2X(s) + 3CuSO4(aq) 3Cu(s) + X2(SO4)3(aq)
[Cu = 64].

26. In the manufacture of iron in the blast furnace, iron (III) oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following, statements are true with respect to these reactions?
A.   The coke is a powerful reducing agent and easily converts the iron oxide to iron
B.   The calcium carbonate reacts with SiO2, an earthly impurity in the ore, to form calcium silicate
C.   The coke will react with the iron produced to form steel
D.   The calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity

jamb past questions and answers on chemistry 2017
The electrons of two atoms Y and Z are arranged in shells as shown above. The bond formed between the atoms of Y and Z is __.
A.   ionic
B.   covalent
C.   dative
D.   metallic

28.A gas sample with an initial volume of 3.25 dm3 is heated and allowed to expand to 9.75 dm3 at constant pressure. What is the ratio of the final absolute temperature to the initial absolute temperature?
A.   3:1
B.   5:2
C.   5:4
D.   8:3 

29.The chemical used for coagulation in water purification is __.
A.   aluminium tetraoxosulphate (VI)
B.   copper tetraoxosulphate (VI)
C.   sodium tetraoxosulphate (VI)
D.   calcium tetraoxosulphate (VI)

30.A liquid that will dissolve fat is __.
A.   hydrochloric acid
B.   calcium hydroxide
C.   kerosene
D.   water

31.When air, which contains the gases: oxygen, nitrogen. carbon dioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are:
A.   nitrogen and carbon dioxide
B.   the rare gases
C.   nitrogen and oxygen
D.   nitrogen and the rare gases 

32.The number of atoms in one mole of a substance is equal to __.
A.   the atomic number
B.   the Avogadro number
C.   the gas constant
D.   the number of electrons.

33.Which of the following terms indicates the number of bonds that can be formed by an atom?
A.   Oxidation number
B.   Valence
C.   Atomic number
D.   Electro-negativity

34.The structural formula of ethanoic acid is __.
jamb past questions and answers on chemistry 2017
35.Environmental pollution is worsened by the release from automobile exhausts of __.
A.   water vapour
B.   steam
C.   smoke
D.   heavy metals

36. What volume of 0.5 mol dm-3 H2SO4 will exactly neutralize 20cm3 of 0.1 mol dm-1 NaOH solution?
A.   2.0 cm3
B.   5.0 cm3
C.   6.8 cm3
D.   8.3 cm3
37.Which of the following is an electrolyte?
A.   Alcohol
B.   Sodium acetate solution
C.   Solid potassium in hydroxide
D.   Mercury

38. Na2S2O3(aq) + 2HCl(aq) 2NaCI(aq) + H2O(l) + SO2(g) + S(s)

Which of the following would introduce the greatest increase in the rate of the chemical reaction above?
A.   An increase in temperature and a decrease in the concentration of the reactants
B.   A decrease in volume and an increase in the pressure of the reactants.
C.   A decrease in temperature and an increase in the concentration of the reactants
D.   An increase in temperature and an increase in the concentration of the reactants

39.Which of the following substances has the lowest vapour density?
A.   Ethanoic acid
B.   Propanol
C.   Dichloromethane
D.   Ethanal

[O= 16, CI = 35.5, H = 1, C = 12]

40.The presence of an impurity in a substance will cause the melting point to __.
A.   be zero
B.   reduce
C.   increase
D.   be stable

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

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