Chemistry past questions and

answers jamb 2024

1. Which of the following elements will exhibit the most
electronegative character?
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(a) Al
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(b) Si
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(c) P
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(d) S
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The correct answer is: (d) S

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2. Acid hydrolysis of nitriles will yield?

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(a) Alkanes
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(b) Aldehydes
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(c) Carboxylic acids

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(d) Alcohols
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The correct answer is: (c) Carboxylic acids

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3. How many isomers of C4H9OH will be tertiary alkanol?

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(a) 1
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(b) 2
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(c) 3
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(d) 4
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The correct answer is: (b) Resonance frequency

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4. Which of the following makes oils distinguished from

fats?
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(a) Oil contains a higher proportion of unsaturation

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(b) Fats contain a higher proportion of unsaturation

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(c) Oil and fats have the same proportion of unsaturation

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(d) Neither oil nor fats have unsaturation

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The correct answer is: (a) Oil contains a higher proportion of

unsaturation
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5. The characteristic crystalline shape of solid water is due

to _____
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(a) Covalent bonds

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(b) Hydrogen bonds

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(c) Ionic bonds

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(d) Metallic bonds

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The correct answer is: (b) Hydrogen bonds

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6. The chemical formula for laughing gas is _____
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(a) NO
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(b) NO2NO2
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(c) N2ON2O
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(d) N2O5N2O5
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The correct answer is: (c) N2ON2O

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7. The sulphide used in coating electric fluorescent tubes is

_____
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(a) Iron (II) sulphide

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(b) Sphalerite
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(c) Zinc sulphide

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(d) Sulphide mineral

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The correct answer is: (c) Zinc sulphide

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8. Calculate the volume in dm3dm3 of oxygen evolved at

s.t.package. When a curent of 5A is passed throught
acidified water for 772s (molar volume of gas at stp. =
22.4 dm3dm3)
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(a) 0.056
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(b) 0.224
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(c) 224000
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(d) 56000
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The correct answer is: (b) 0.224

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9. Hydrogenation of Benzene to cyclohexane is called

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(a) Cracking
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(b) Polymerisation
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(c) Reforming
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(d) Aromatization
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The correct answer is: The examiner had aromatization in mind

but it does not apply
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10. The pollutant that contributes to the depletion of the

ozone layer is _____
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(a) CF
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(b) CS
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(c) CCl
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(d) CFC
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The correct answer is: (d) CFC

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11. What changes sodium hydroxide pellets to liquid?

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(a) Oxygen
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(b) Water vapour

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(c) Carbon (IV) oxide

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(d) Nitrogen
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The correct answer is: (b) Water vapour

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12. The compound used as 'antifreeze' in car radiators in

cold regions of the world is _____
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(a) Ethanol
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(b) Ethylene glycol

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(c) Ethanal
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(d) Propan-1,2-diol
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The correct answer is: (b) Ethylene glycol

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13. What are the laws that form the general gas equation?
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(a) Boyle's and Charles' laws

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(b) Boyle's Charles' and Graham's laws

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(c) Gaps between the coils

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(d) The area of the coil

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The correct answer is: (c) Gaps between the coils

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14. Chlorine, bromine, and iodine resemble each other in

that all
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(a) Dissolve in alkalis

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(b) Displace each other from solutions of their salts

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(c) React violently with hydrogen on heating

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(d) Are electron donors

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The correct answer is: (a) Dissolve in alkalis

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15. The method suitable for separating suspended particles

in liquid is _____
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(a) Decantation
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(b) Distillation
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(c) Centrifugation
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(d) Chromatography
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The correct answer is: (c) Centrifugation

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16. A hydrocarbon X has a molar mass of 26 and a carbon

atom percentage of 92.3%. What is its molecular formula?
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(a) C2H2C2H2
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(b) C2H6C2H6
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(c) CH4CH4
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(d)
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C3H8C3H8
The correct answer is: (a) C2H2C2H2
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17. Silica gel, when exposed to air, turns liquid. What kind
of substance is it?
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(a) Deliquescent
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(b) Hygroscopic
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(c) Efflorescent
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(d) Entropy
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The correct answer is: (a) Deliquescent

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18. In an equilibrium reaction, which of the following

conditions indicate that the maximum yield of the product
will be obtained?

△H=T△S△H=T△S
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(a) Equilibrium constant is very large

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(b)
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(c) ΔH≥TΔSΔH≥TΔS
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(d) Equilibrium constant is less than zero

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The correct answer is: (a) Equilibrium constant is very large

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19. Under high pressure, real gases do not obey laws

because their molecules
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(a) Have become more energetic

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(b) Have become less energetic

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(c) Have become smaller in size

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(d) Have become larger in size

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The correct answer is: (b) Have become less energetic

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20. The salt responsible for temporary hardness is _____

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(a) Calcium sulphate

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(b) Magnesium chloride

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(c) Calcium bicarbonate

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(d) Magnesium sulphate

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The correct answer is: (c) Calcium bicarbonate

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21. Common salt (Nacl) is used to preserve foods. Which of

the following properties can be used to determine its purity
before use?
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(a) Solubility in water

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(b) Melting point

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(c) Relative density

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(d) Crystalline nature

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The correct answer is: (b) Melting point
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22. The rate of a chemical reaction is NOT affected by one

of these factors
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(a) Color
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(b) Concentration
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(c) Presence of light

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(d) Surface area

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The correct answer is: (a) Color

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23. The functional group represented in the compound

below is _____
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(a) Alkanol
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(b) Alkanal
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(c) Alkanone
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(d) Alkanoate
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The correct answer is: (b) Alkanal

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24. On exposure to the atmosphere, a hydrated salt loses

its water of crystallization to become anhydrous. This
phenomenon is referred to as _____
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(a) Efflorescence
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(b) Deliquescence
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(c) Hydroscopy
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(d) Hydrolysis
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The correct answer is: (a) Efflorescence

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25. Which of the following statements is true of the

electrochemical series?
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(a) Electropositivity of metals increases down the series

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(b) Electropositivity of non-metals decreases down the

series
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(c) Electronegativity of non-metals decreases

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(d) Electropositivity of metals decreases down the series

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The correct answer is: (d) Electropositivity of metals decreases

down the series
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26. Which of the following pairs are both substances

deliquescent?
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(a) CaCl2CaCl2 and H2SO4H2SO4

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(b) NaOH and
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MgSO4MgSO4.7H2O7H2O
(c) CaCl2CaCl2 and NaOH
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(d) CuO and NaCl

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CaCl2CaCl2 and NaOH

The correct answer is: (c)
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27. The bond formed between H2OH2O and H+H+ to form

the hydroxonium H3O+H3O+ is
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(a) Dative
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(b) Covalent
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(c) Electrovalent
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(d) Ionic
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The correct answer is: (a) Dative

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28. Gas molecules are said to be perfectly elastic because

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(a) They collide without loss of energy

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(b) They move about in straight lines

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(c) The distances between them are neglible

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(d) The volume occupied by them is negligible

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The correct answer is: (a) They collide without loss of energy
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29. A solid that absorbs water from the atmosphere and

forms an aqueous solution is _____
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(a) Hydrophilic
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(b) Efflorescent
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(c) Deliquescent
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(d) Hygroscopic
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The correct answer is: (c) Deliquescent

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30. Which of the following can undergo both addition

reaction and substitution reaction?
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(a) Benzene
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(b) Pentane
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(c) Propane
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(d) Hexane
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The correct answer is: (a) Benzene

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31. Naming of the organic

compound CH3(CH2)4CH2CH2NH2CH3(CH2)4CH2CH2NH2
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(a) Pentaneamine
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(b) Heptanamine
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(c) Hexanamine
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(d) Octanamine
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The correct answer is: (b) Heptanamine
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32. 2Cl(aq)−2Cl(aq)− = Cl2(g)Cl2(g) + 2e(eq)−2e(eq)−

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The above half-cell reaction occurring at the anode during

the electrolysis of dilute ZnCl2 solution is?
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(a) Ionization
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(b) Oxidation
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(c) Reduction
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(d) Recombination
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The correct answer is: (b) Oxidation

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33. CHCl3+Cl2→HCL+CCl4CHCl3+Cl2→HCL+CCl4
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The reaction above is an example of?

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(a) An addition reaction

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(b) A decomposition reaction

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(c) A substitution reaction

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(d) A condensation reaction

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The correct answer is: (c) A substitution reaction

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34. cxHy+4O2=3Co2+2H2OcxHy+4O2=3Co2+2H2O. The

hydrocarbon, CxHyCxHy, in the reaction above is?
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(a) Butene
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(b) Butane
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(c) Butyne
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(d) Butanone
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The correct answer is: (b) Butane

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35. One method of driving the position of equilibrium of an

endohermic reaction forward is to?
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(a) Increase temperature at constant pressure

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(b) Decrease pressure at constant temperature

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(c) Cool down the apparatus with water

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(d) Decreases temperature at constant pressure

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The correct answer is: (a) Increase temperature at constant

pressure
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36. 0.92 of ethanol when burned raised the temperature of

50g of water by 28.6K. Calculate the heat of combustion of
ethanol. [C = 12, O = 16, H = 1, specific heat capacity of
water = 4.2Jg−1K−14.2Jg−1K−1]
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(a) +3000KJmol−1+3000KJmol−1
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(b) +300KJmol−1+300KJmol−1
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(c) −300KJmol−1−300KJmol−1
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(d) −3000KJmol−1−3000KJmol−1
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The correct answer is: (c) −300KJmol−1−300KJmol−1

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37. The repeating unit in natural rubber is _____

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(a) Alkyne
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(b) Isoprene
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(c) n-propene
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(d) neoprene
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The correct answer is: (b) Isoprene

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38. What current in amperes will deposit 2.7g of aluminium

in 2 hours? [Al = 27, F = 96500Cmol−196500Cmol−1]
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(a) 32
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(b) 8
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(c) 4
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(d) 16
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The correct answer is: (c) 4

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39. Steam changes the colour of anhydrous cobalt (II)

choride from
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(a) Blue to pink

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(b) Red to white

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(c) White to green

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(d) White to blue

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The correct answer is: (a) Blue to pink

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40. Which of the following will change when a catalyst is

added to a chemical reaction?
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(a) The activation energy

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(b) The potential energy of the reactants

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(c) The heat of the reaction

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(d) The potential energy of the product

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The correct answer is: (a) The activation energy