www.prep.ng: JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2018 (TEXT)

Wednesday, 27 February 2019

JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2018 (TEXT)

jamb past questions and answers on chemistry 2018, jamb mock past questions

1. The periodic classification of the elements is an arrangement of the elements in order of their __.
A. atomic weights
B.  isotopic weights
C.  molecular weights
D.  atomic numbers

2.   If 1 litre of 2.2M sulphuric acid is poured into a bucket containing 10 litres of water, and the resulting solution mixed thoroughly, the resulting sulphuric acid concentration will be  __.
A.   2.2 M
B.   1.1 M
C.   0.22 M
D.   0.11 M
jamb past questions and answers on chemistry 2018

3.  In the above experiment (Fig. 1) the litmus paper will initially __.
A.   be bleached
B.   turn green
C.   turn red
D.   turn blue

4.   A correct electro-chemical series can be obtained from K, Na, Ca, Al, Mg. Zn, Fe, Pb, H, Cu, Hg, Ag, Au by interchanging __.
A.   Al and Mg
B.   Zn and Fe
C.   Zn and Pb
D.   Pb and H

5.   A basic postulate of the kinetic theory of gases is that the molecules of a gas move in straight lines between collisions. This implies that  __.
A.   collisions are perfectly elastic
B.   forces of repulsion exist
C.   forces of repulsion and attraction are in equilibrium
D.   collisions are inelastic.

6.   On which of the following is the solubility of a gaseous substance dependent? 
I. Nature of solvent 
II. Nature of solute 
III. Temperature 
IV. Pressure

A.   I, II, III and IV
B.   I and II only
C.   II only
D.   I, III and IV only.

7.   Which of the following statements is correct about the periodic table?
A.   Elements in the same period have the same number of valence electrons 
B.   The valence electrons of the elements in the same period increase progressively across the period.
C.   Elements in the same group have the same number of electron shells
D.   The non-metallic properties of the elements tend to decrease across each period

8.   The boiling of fat and aqueous caustic soda is referred to as __.
A.   hydrolysis
B.   esterification
C.   acidification
D.   saponification

9.   Which of the following pairs of substances will react further with oxygen to form a higher oxide?
A.   CO2 and H2O
B.   NO and H2O
C.   CO and CO2
D.   SO2 and NO 

10. In the preparation of oxygen by heating KCIO3 in the presence of MnO2, only moderate heat is needed because the catalyst acts by __.
A.   lowering the pressure of the reaction
B.   increasing the surface area of the reaction
C.   increasing the rate of the reaction
D.   lowering the energy barrier of the reaction

11. Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of sand, water and methanoic acid?
A.   Fractional distillation
B.   Filtration followed by distillation
C.   Neutralization with sodium hydroxide followed by distillation
D.   Neutralization with sodium hydroxide followed by filtration 

12. A quantity of electricity liberates 3.6 g of silver from its salt. What mass of aluminium will be liberated from its salt by the same quantity of electricity?
A.   2.7 g
B.   1.2 g
C.   0.9 g
D.   0.3 g

[Al = 27, Ag = 108].

13. Suitable reagents for the laboratory preparation of nitrogen are  __.
A.   sodium dioxonitrate (III) and ammonium chloride
B.   sodium trioxonitrate (V) and ammonium chloride
C.   sodium chloride and ammonium trioxonitrate (V)
D.   sodium chloride and ammonium diozonitrate (III).

14. The number of electrons in the valence shell of an element of atomic number 14 is __.
A.   1
B.   2
C.   3
D.   4

15. What volume of oxygen will remain after reacting   8cm3 of hydrogen gas with 20cm3 of oxygen gas?
A.   10cm3
B.   12cm3
C.   14cm3
D.   16cm3

16. If one of the following oxides is heated with hydrogen or carbon using a Bunsen burner, it is not reduced to the metal. Which one is it?
A.   lead oxide
B.   Magnesium oxide
C.   Copper oxide
D.   Tin oxide

17.The name for jamb past questions and answers on chemistry 2018
A.   1 -methylpentane
B.   3-methylbutane
C.   2-methylbutane
D.   1 -dimethylpropane

18. An aqueous solution of a metal salt M, gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia. Therefore, the cation in M is 
A.   Zn2+
B.   Ca2+
C.   Al3+
D.   Pb2+

19. What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution?
A.   0.40 mol dm-3
B.   0.50 mol dm-3
C.   0.05 mol dm-3
D.   0.30 mol dm-3
[Na = 23, O =16, H =1]

20.  How many atoms are present in 6.0g, of magnesium?
A.   1.20 x 1022
B.   2.41 x 1022
C.   1.51 x 1023
D.   3.02 x 1023
[Mg =24, NA =6.02 x 1023 mol-1]. 

21. The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is __.
A.   carbon - 14
B.   Phosphorus - 32
C.   Cobalt
D.   Iodine - 131

22. Beryllium and Aluminium have similar properties because they __.
A.   are both metals
B.   belong to the same group
C.   belong to the same period
D.   are positioned diagonally to each other

jamb past questions and answers on chemistry 2018


 24.  (i) 3CuO(s) + 2NH3(g)  3Cu(s) + 3H2O(l) + N2(g)
(ii) 2NH3(g) + 3CI2(g)  6HCI(g) + N2(g)
(iii) 4NH3(g) + 3O2(g)  6H2O(l) + 2N2(g).
The reactions represented by the equations above demonstrate the
A.   basic properties of ammonia
B.   acidic properties of ammonia
C.   reducing properties of ammonia
D.   oxidizing properties of ammonia

25. The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is __.
A.   Na2SO4
B.   Na2SO3
C.   Na2S
D.   Na2CO3

26. The refreshing and characteristic taste of soda water and other soft drinks is as a result of the presence in them of __.
A.   carbon (IV) oxide
B.   carbon (II) oxide
C.   soda
D.   glucose

27. Which of the following are mixtures? i. Petroleum ii. Rubber latex. iii. Vulcanizer's solution iv. Carbon (II) sulphide
A.   i, ii and iii
B.   i, ii and iv
C.   i and ii only
D.   i and iv

28. A balanced chemical equation obeys the law of __.
A.   conservation of mass
B.   definite proportions
C.   multiple proportions
D.   conservation of energy

29.  A given amount of gas occupies 10.0 dm3 at 4 atm and 273°C. The number of moles of the gas present is
A.   0.89 mol
B.   1.90 mol
C.   3.80 mol
D.   5.70 mol
[Molar volume of a gas at stp. = 22.4 dm3]

30. According to Charles' law, the volume of a gas becomes zero at __.
A.   0°C
B.   -100°C
C.   -273°C
D.   -373°C

31. A substance that is used as a ripening agent for fruits is __
A.   ethene
B.   propane
C.   methane
D.   butane

32. The Sulphide which is insoluble in dilute hydrochloric acid is __.
A.   FeS
B.   CuS
C.   ZnS
D.   Na2S

33. What is the PH of 0.001 moldm-3 solution of the sodium hydroxide?
A.   14
B.   13
C.   12
D.   11

34.The type of bonding in [Cu(NH3)4]2+ is __.
A.   coordinate
B.   electrovalent
C.   metallic
D.   covalent.

35. Which of the following is an example of a chemical change?
A.   dissolution of salt in water
B.   rusting of iron
C.   melting of ice
D.   separating a mixture by distillation

36. To what temperature must a gas at 273K be heated in order to double both its volume and pressure?
A.   298K
B.   546K
C.   819K
D.   1092K

37. According to the Kinetic Theory, an increase in temperature causes the kinetic energy of particles to:
A.   decrease
B.   increase
C.   be zero
D.   remain constant

38. An element used in the production of matches is __.
A.   nitrogen
B.   aluminium
C.   copper
D.   Sulphur

39. Which of the following gases may not be dried with concentrated sulphuric acid?
A.   HCl(g)
B.   NH3
C.   CI2
D.   SO2

40.Consecutive members of an alkane homologous series differ by __.
A.   CH
B.   CH2
C.   CH3
D.   CnHn

ANSWERS

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



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