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Thursday, 28 February 2019

JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2016 (TEXT)


jamb past questions and answers on chemistry 2016

1.     An element X has twoin the ratio 1:3. The relative atomic mass of x would be __.
A.   20.5
B.   21.0
C.   21.5
D.   22.0

2.   200cm3 of oxygen diffuse through a porous plug in 50 seconds. How long, will 80cm3 of methane (CH4) take to diffuse through the same porous plug under the same conditions?
A.   40 sec
B.   20 sec
C.   14 sec
D.   7 sec

3.   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
 jamb past questions and answers on chemistry 2016

4.   The diagram above represents an atom of __.
A.   magnesium
B.   helium
C.   chlorine
D.   neon

5.   Which of the following gases is the most dangerous pollutant?
A.   Hydrogen sulphide.
B.   Carbon Monoxide
C.   Sulphur(iv)oxide
D.   Carbon Dioxide

6.   A Side effect or Soft water is that __.
A.   It gives offensive taste
B.   excess calcium is precipitated
C.   it attacks lead contained in pipes
D.   it encourages the growth of bacteria.

7.   Farmlands affected by crude oil spillage can be decontaminated by __.
A.   adding acidic solutions
B.   using aerobic bacteria
C.   pouring water on the affected area
D.   burning off the oil from the area.

8.   Which of the following functional groups will give gas bubbles when treated with a saturated solution of sodium hydrogen trioxocarbonate(iv)?  jamb past questions and answers on chemistry 2016
9.   The oxidation state of Cr in K2Cr2O7 is __.
A.   +7
B.   +6
C.   +5
D.   4

10. 2Na2O2(s) + 2H2O(l) 4Na0H(s) +O2.
The substance that is oxidized in the reaction above is __.
A.   2Na202(s)
B.       NaOH(aq)
C.       H2O(l)
D.       O2(g)

11. 
jamb past questions and answers on chemistry 2016
Z in diagram above represents __.
A.   heat of reaction
B.   activation energy
C.   free energy
D.   entropy of reaction

12. The nucleus of an atom contains
A.   protons only
B.   neutrons only
C.   protons and electrons
D.   protons and neutrons

13. Which of the following does NOT happen when a Zinc rod is introduced into a solution of Copper(II)sulphate?
A.   Electrons flow towards the zinc rod
B.   The Zinc rod dissolves
C.   The temperature of the soil chances
D.   The blue colour of the solution gradually disappears.

14. Which of the following statements is correct during the electrolysis of a caustic soda solution using platinum electrodes?
A.   Oxygen gas is given off at the cathode
B.   Hydrogen gas is given off at the anode
C.   Sodium metal is deposited at the cathode
D.   Alkalinity at the cathode increases.

15. Which of the following statements is INCORRECT?
A.   Fractional distillation of crude petroleum will give the following hydrocarbon fuels in order of increasing boiling point.  Butane < Petrol < Kerosene
B.   H2C = CH2 will serve as a monomer in the preparation of polythene
C.   both but-i-ene and but-i-yne will decolourize bromine readily
D.   Calcium carbide will react with water to form any alkyne

16. The iron(iii)oxide impurity in bauxite can be removed by __.
A.   fractional crystallization in acid solution
B.   dissolution in sodium hydroxide and filtration
C.   extraction With concentrated ammonia and re-precipitation
D.   electrolysis of molten mixture

17. Aluminium is extracted commercially from its ore by
A.   heating aluminium oxide with coke in a furnace
B.   the electrolysis of fused aluminium oxide in cryolite
C.   treating cryolite with sodium hydroxide solution under pressure
D.   heating sodium aluminium silicate to a high temperature

18. Which of the following compounds gives a yellow residue when heated and also reacts with aqueous sodium hydroxide to give a white gelatinous precipitate soluble in excess sodium hydroxide solution?
A.   (NH4)2CO3
B.   ZnCO3
C.   Al2(SO4)3
D.   PbCO3

19. The least easily oxidized of the metals below is __.
A.   Cu
B.   Na
C.   Zn
D.   Al

20.Which of the following chlorides would exhibit the least ionic character?
A.       MgCl2
B.   CaCl2
C.   LiCl
D.   AlCl3

21. Which of the following CANNOT be obtained by fractional distillation of petroleum?
A.   Ether
B.   Methane
C.   Butane
D.   Hydrogen

22. Which of the following is used as an anti-knock in automobile engines?
A.   tetramethylsilane
B.   leadtetraethyl
C.   Glycerol
D.   n-heptane

23. The Avogadro number of 24g of magnesium is the same as that of __.
A.   1g of hydrogen molecules
B.   16g of oxygen molecules
C.   32g of Oxygen molecules
D.   35.5g of chlorine molecules.

24. In an electrolyte set-up to protect iron from corrosion, the iron is __.
A.   made the cathode
B.   made the anode
C.   used with a metal of lower electro-positive potential
D.   initially coated with tin

25. The removal of rust from iron by treatment with tetraoxosulphate (vi) acid is based on the __.
A.   hydrolysis of the iron
B.   reaction of acid with base
C.   oxidation of the rust
D.   dehydration of the iron.

26. The substance often used for vulcanization of rubber is __.
A.   Chlorine
B.   hydrogen peroxide
C.   Sulphur
D.   tetraoxosulphate (vi) acid

27. Metals of the first transition series have special properties which are different from those of groups I and II elements because they have partially filled.
A.   s-orbitals
B.   p-orbitals
C.   d-orbitals
D.   f-orbitals

28. A particle that contains 11 protons, 12 neutrons and 10 electrons is probably a __.
A.   Neutral non-metal
B.   metallic ion
C.   non-metallic ion
D.   neutral metal.

29. A catalyst increases the rate of a chemical reaction by providing a path that __.
A.   raises the activation energy
B.   increases the temperature
C.   lowers the activation energy
D.   increases the concentration

30. A metal M displaces Zinc from ZnCl2 solution. This shows that __.
A.   electrons flow from Zinc to M
B.   M is more electropositive than Zinc
C.   M is more electronegative than Zinc
D.   Zinc is more electropositive than M.

31. Calculate the quantity of electricity in coulombs required to liberate 10g of copper from a copper compound.
A.   32395.5
B.   30156.3
C.   60784.5
D.   15196.6
[Cu 64    F = 96500c]

32. The IUPAC names for the compounds CH3COOH and CH2 = CH2 are respectively __.
A.   acetic acid and ethane
B.   ethanoic- acid and ethene
C.   methanoic acid and ethylene
D.   ethanol and ethene.

33. The boiling point of water is higher than that of methanol because __.
A.   water is an oxide while methanol is an alcohol
B.   inter-molecular forces in water are stronger than those in methanol
C.   Water is an inorganic compound while methanol is organic
D.   Water is a compound while methanol is a covalent compound

34. 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 2016

35. Which combination of the following statements is correct? 1. Lowering the activation energy 2. conducting the reaction in a gaseous state. 3. Increasing the temperature. 4. removing the products as soon as they are formed. 5. Powdering the reactant if solid
A.   1. 2 and 3
B.   1, 3 and 5
C.   2, 3 and 5
D.   3 and 4

36. An element with atomic number twelve is likely to be __.
A.   electrovalent with a valency of 1.
B.   electrovalent with a valency of 2.
C.   covalent with a valency of 2.
D.   covalent with valency of 4.

37. Which of the following physical properties decreases across the periodic Table?
A.   ionization potential
B.   Electron affinity
C.   Electro-negativity
D.   Atomic radius.

38. If a gas occupies a container of volume 146cm3 at 18c and 0.971 atm, its volume in cm3 at s.t.p is __.
A.   133
B.   146
C.   266
D.   292

39. 50cm3 of carbon(ii)oxide was exploded with 150cm3 of air containing 20% oxygen by volume, which of the reactants was in excess?
A.   Carbon(ii)oxide
B.   Carbon(iv)oxide
C.   Oxygen
D.   Nitrogen

40. The formula CH2O for ethanoic acid is regarded as its __.
A.   molecular formula
B.   general formula
C.   empirical formula
D.   Structural formula


ANSWERS

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

JAMB PAST QUESTIONS AND ANSWERS ON CHEMISTRY 2017 (TEXT)

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

27.
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

ANSWERS
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