Chemistry 2001 JAMB past questions and answers (IN DETAILS)

by clever academyNovember 03, 20185 Comments


2001 JAMB CHEMISTRY
Use the graph below to answer question 1 and 2

1.     How long does it take all the solid to melt?
(a) 1.0 mins


(b) 2.5 mins
(c)  3.0 mins
(d) 6.0 mins
ANSWER: B



2.     If the gas is cooled, at what temperature will it start to condense?
(a) 250oC
(b) 175oC
(c)  150oC
(d) 125oC
Answer: A

3.     What mass of water is produced when 8.0 g of hydrogen reacts with excess oxygen?
(a) 8.0 g
(b) 16.0 g
(c)  36.0 g
(d) 72.0 g
Answer: D


EXPLANATION: Using the equation; 2H2 + O2 à 2H2O,
                             From the equation above,
                       4g of Hydrogen produces 36g of water
Therefore, 8g of Hydrogen will produce = 36 X 8/4
                                              =72g of H2O

4.     25cm3 of gas X contains Z molecules at 15oC and 75mmHg. How many molecules will 25cm3 of another gas Y contain at the same temperature and pressure?
(a) Y
(b) Z
(c)  2Y
(d) 2Z
ANSWER: B

5.     An oxide XO2 has a vapour density of 32. What is the atomic mass of X?
(a) 12
(b) 14
(c)  20
(d) 32
ANSWER: D


EXPLANATION: RMM = 2 X V.D
XO2 = X + O2 = 2 X 32 = X + 32
X = 64 – 32 = 32

6.     Which of the following statements is correct about the average kinetic energy of the molecules of a gas?
(a) It increases at constant pressure
(b) It increases with increase in volume
(c)  In increases with increase in pressure
(d) It increases with increase in temperature
ANSWER: D



7.     Four elements W, X, Y, and Z have atomic numbers 2, 6, 16 and 20 respectively. Which of this elements is a metal?
(a) W
(b) X
(c)  Y
(d) Z
ANSWER: D

8.     A particle that contains 9 protons, 10 neutrons, and 10 electrons is a___
(a) Neutral atom of a metal
(b) Neutral atom of a non-metal
(c)  Negative ion
(d) Positive ion
ANSWER: C  CLICK HERE TO READ MORE



9.     The diagram below represents the formation of __

(a) A covalent bond
(b) An electrovalent bond
(c)  A coordinate covalent bond
(d) A metallic bond
ANSWER: A

SEE ILLUSTRATION BELOW
COVALENT BONDING BETWEEN TWO CHLORINE ATOMS



10.                        Cancerous growth are cured by exposure to ___
(a) Alpha rays
(b) X-rays
(c)  Gama rays
(d) Beta rays
ANSWER: B

11.                        Millikan’s contribution to the development of atomic theory is the determination of _
(a) Charge to mass ratio
(b) Charge on electron


(c)  Cathode rays
(d) Positive rays
ANSWER: B

12.                        An element X6 with relative atomic mass of 16.2 contains two isotopes 168X  with relative abundance of 90% and m0X with relative abundance of 10%. The value of m is_
(a) 18
(b) 16
(c)  14
(d) 12
ANSWER: A
EXPLANATION: [90 X 16/100 + 10 X M/100]
           = (14.4) + (0.1 X M) = 16.2
           = 0.1 X M = (16.2 – 14.4)
           = 0.1 X M = 1.8
Therefore, M= 1.8/0.1 = 18



13.                        Phosphorus is stored under water to prevent it from__
(a) Becoming inert
(b) Catching fire
(c)  Dehydrating
(d) Smelling
ANSWER: B

14.                        What is the decrease in volume of air when pyrogallol is shaken with 30.00cm3 of air?
(a) 0.06cm3
(b) 0.63cm3
(c)  6.30cm3
(d) 25.00cm3
ANSWER: C
EXPLANATION: Air contains 21% of oxygen and pyrogallol absorbs or removes oxygen from the air.
Therefore, 21% of 30cm3, will give;
           21 X 30/100
        = 6.3cm3



15.                        The chemical used for coagulation in water purification is__
(a) Sodium tetraoxosulphate VI
(b) Aluminium tetraoxosulpate VI
(c)  Calcium tetraoxosulphate VI
(d) Copper tetraoxosulphate VI
ANSWER: B

16.                        Deliquenscent substances are used for __
(a) Melting
(b) Drying
(c)  Cooling
(d) Wetting
ANSWER: B



17.                        Environmental pollution is worsened by the release from automobile exhausts of __
(a) Smoke
(b) Heavy metals
(c)  Steam
(d) Water vapour
ANSWER: A

18.                        The pollution from petroleum spillage in rivers and lakes can best be dispersed by__
(a) Evaporation
(b) Pouring organic solvent
(c)  Passing off ships through the area
(d) Pouring detergents
ANSWER: D

19.                        Pure solvents are obtained by_____
(a) Extraction


(b) Evaporation
(c)  Distillation
(d) Condensation
ANSWER: C

Use the solubility curves below to answer questions 20 and 21



20.                        If 1 dm3 of saturated solution of L at 60oC is cooled to 25oC, what amount in mole will separate out?
(a) 1.00oC
(b) 0.750C
(c)  0.500C
(d) 0.250C
ANSWER: B


EXPLANATION: THAT IS (1.5 – 0.75) = 0.75.
The diagram below is the solubility curve of a solute X
21.                        At what temperature are the solubilities of L and K are the same?
(a) 100o
(b) 90o
(c)  82o
(d) 75o
ANSWER: C

22.                        Ethanoic acid is __


(a) Monobasic
(b) Dibasic
(c)  Tribasic
(d) Unionizeable
ANSWER: A
EXPLANATION: Ethanoic acid has one replaceable hydrogen ion ie.
CH3COOH ßà CH3OO + H+

23.                        As the concentration of an electrolyte reduces, the conductivity ___
(a) Increases
(b) Decreases
(c)  Is unaffected
(d) Reduces to zero
ANSWER: B



24.                        3Cu(s) + 8HNO3(aq) à 3Cu(NO3)2(aq) + 4H2O(l) + 2NO(g)
In the reaction above, copper is ______
(a) An oxidizing agent
(b) A reducing agent
(c)  An electron acceptor
(d) A base
ANSWER: B



25.                        In which of the following reactions does reduction takes place?
(a) Cr – 2e- à Cr2+
(b) 2H+ + 2e- à H2
(c)  Fe2+ + e- à Fe3+
(d) 2O2- à O2 + 4e-
ANSWER: B

26.                        In which of the following reactions has the oxidation number of nitrogen increased?
(a) 2NO(g) + Cl2(g) à 2NOCL2(l)
(b) 2NO(g) + Br2(g) à 2NOBr(l)
(c)  2NO(g) + O2(g) à 2NO2(g)
(d) FeSO4(aq) + NO(g) à Fe(NO)SO4(s)
ANSWER: C CLICK HERE FOR MORE UNDERSTANDING ON HOW TO CALCULATE OXIDATION NUMBER

27.                        A metal M displaces zinc Chloride solution. This shows that___
(a) Electrons flows from zinc to M
(b) M is more electropositive than zinc
(c)  M is more electronegative than zinc
(d) Zinc is above hydrogen in the series
ANSWER: B



28.                        What current in amperes will deposit 2.7gt of aluminium in 2 hours?
(a) 4
(b) 8
(c)  16
(d) 32 [Al=27, F= 96500C/mol]
ANSWER:  A
EXPLANATION:Al3+ + 3e- à Al
From equation, 3F = 27g Al
That is, 3 X 96500 coulombs deposit 27g of Al
Therefore, 2.7g of Al will require 3 X 96500 X 2.7/27
              = 28950 coulombs
Q = It = 28950
SO WE HAVE THAT,
I X 120 X 60 = 28950
THERFORE, I = 28950/(120 X 60)
                      = 4A

29.                        When change in enthalpy is negative, a reaction is said to be____
(a) Exothermic
(b) Endothermic
(c)  Ionic
(d) Reversible
ANMSWER: A READ MORE ON EXOTHERMIC AND ENDOTHERMIC REACTIONS

30.                        C(s) + 2S(g) à CS2(g), H= +89kJ/mol. The chemical equation implies that?
(a) 89kJ 0f energy is released
(b) 89kJ 0f energy is absorbed
(c)  Each of carbon and sulphur has 89kJ of energy
(d) Both carbon and sulphur contributes  89kJ of energy
ANSWER: B

31.                        NH3(s) + HCI(g) à NH4CL2(s). The entropy change of the system is___
(a) Positive
(b) Negative
(c)  Zero
(d) Indeterminate
ANSWER: B READ MORE ON ENTROPY AND ITS CALCULATIONS




32.                        Which of the following best explains the increase in the rate of a chemical reaction as the temperature rises?
(a) The collision frequency of the molecules increases
(b) A lower proportion of the molecules has the necessary minimum energy to react
(c)  The molecular collision becomes more violent
(d) The bonds in the reacting molecules are more readily brocken
ANSWER: C READ MORE ON EFFECTIVE COLLISION

33.                        P(g) + Q(g) à 3R(g) + S(g), change in enthalpy is negative. Which of the following will increase the yield of R?
(a) Increasing the temperature
(b) Adding a positive catalyst
(c)  Using a larger closed vessel
(d) Removing some S
ANSWER: D READ MORE ON ENTHALPY



34.                        2SO2(g) + O2(g) à 2SO3(g), H= -189KJ/MOL. The equilibrium constant for the reaction is increased by
(a) The addition of a catalyst to the system
(b) Increasing the surface area of the vessel
(c)  Increasing the temperature of the system
(d) Increasing the pressure of the system
ANSWER: C

35.                        A burning candle produces water and__
(a) Oxtgen
(b) Hydrogen
(c)  Carbon (II) oxide
(d) Carbon (IV) oxide
ANSWER: D

36.                        When chloride is passed inside water and the resulting solution exposed to sunlight, the product formed are__
(a) Hydrochloric acid and oxygen
(b) Chlorine gas and oxochlorate(I)acid
(c)  Oxygen and oxochlorate acid
(d) Chlorine gas and hydrogen
ANSWER: A

37.                         C12H22O11(g) + H2SO4(g) à 12C(g) + 11H2O(l) + H2SO4(aq). In the reaction, tetraoxosulphate (vi) acid functions as__
(a) A catalyst
(b) A reducing agent
(c)  An oxidizing agent
ANSWER: D
(d) A dehydrating agent



38.                        The gas that can best be collected by downward displacement of air is__
(a) Ammonia
(b) Carbon (IV) oxide
(c)  Chlorine
(d) Sulphur (iv) oxide
ANSWER: A

39.                        When sodium reacts with water, the resulting solution is__
(a) Acidic
(b) Alkaline
(c)  Weakly acidic
(d) Neutral
ANSWER: B



40.                        The main impurity in iron ore during the extraction of iron is__
(a) Carbon (IV) oxide
(b) Sulphur (II) oxide
(c)  Silicon (IV) oxide
(d) Sulphur (IV) oxide
ANSWER: C

41.                        Which of the following metals burn with a brick-red flame?
(a) Mg
(b) Pb
(c)  Ca
(d) Na
ANSWER: C

42.                        Catalytic hydrogenation of benzene produces___
(a) Margarine
(b) Cyclohexane
(c)  Cyclohexene
(d) Oil
ANSWER: B



43.                        Which of the following represents hybridization of the ethyne?
(a) SP3
(b) SP2
(c)  SP
(d) SP2d
ANSWER: C

44.                        A trihydric alkanol is__
(a) Glycol
(b) Glycerol
(c)  Ethanol
(d) Phenol
ANSWER: B



45.                        Fermentation is__
(a) Conversion of sugar to alcohol in the presence of yeast
(b) Conversion of alcohol to sugar in the presence of yeast
(c)  Breaking down of carbohydrate to glucose
(d) Breaking down of sugar to carbohydrate
ANSWER: A



46.                        During the vulcanization of rubber, sulphur is added to___
(a) Act as a catalyst
(b) Bind rubber molecules together
(c)  Break down rubber polymer
(d) Lengthen the chain of rubber
ANSWER: B

47.                        A characteristic reaction of the compound with the general formula Cn H2n is __
(a) Polymerization
(b) Substitution
(c)  Esterification
(d) Decarboxylation
ANSWER: A



48.                        The general formula for the alkanals is___
(a) R2CO
(b) RCHO
(c)  ROH
(d) RCOOR
ANSWER: B

49.                        The pair of organic compounds that are isomers is ____
(a) Ethanol and propanone
(b) Benzene and methylbenzene
(c)  But-1-ene and but-2-ene
(d) Trichloromethane and tetrachloromethane
ANSWER: C

50.                        Proteins in acid solutions undergo
(a) Substitution
(b) Fermentation
(c)  Hydrolysis
(d) polymerization


ANSWER: C


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