41. What is the major product when benzene reacts with concentrated HNO₃ and H₂SO₄?
a) Nitrobenzene
b) Benzene sulfonic acid
c) Phenol
d) Benzoic acid
Answer: a) Nitrobenzene
Explanation: The reaction of benzene with concentrated HNO₃ and H₂SO₄ produces nitrobenzene through an electrophilic substitution reaction.
42. Which of the following statements about alkynes is false?
a) Alkynes have at least one triple bond.
b) Alkynes are more acidic than alkanes.
c) Alkynes are saturated hydrocarbons.
d) Alkynes can undergo addition reactions.
Answer: c) Alkynes are saturated hydrocarbons.
Explanation: Alkynes are unsaturated hydrocarbons because they contain at least one triple bond, while saturated hydrocarbons have only single bonds.
43. Which compound is formed from the dehydration of alcohols?
a) Alkene
b) Alkane
c) Alkyne
d) Ether
Answer: a) Alkene
Explanation: The dehydration of alcohols results in the formation of alkenes by removing a water molecule (H₂O).
44. Which of the following compounds is most likely to undergo addition reactions?
a) Ethane
b) Ethylene
c) Acetylene
d) All of the above
Answer: b) Ethylene
Explanation: Ethylene (C₂H₄) is more reactive than ethane and acetylene in addition reactions due to its double bond.
45. Which of the following aromatic compounds is a strong electrophile?
a) Toluene
b) Benzene
c) Nitrobenzene
d) Phenol
Answer: c) Nitrobenzene
Explanation: Nitrobenzene is a strong electrophile due to the electron-withdrawing nitro group (-NO₂) which makes the aromatic ring more susceptible to electrophilic substitution.
46. Which of the following reactions can be used to distinguish between alkanes and alkenes?
a) Addition of Br₂
b) Hydrogenation
c) Dehydrogenation
d) Cracking
Answer: a) Addition of Br₂
Explanation: The addition of Br₂ to alkenes will result in the decolorization of bromine water, while alkanes do not react, making this a good distinguishing test.
47. What is the hybridization of the carbon atoms in 1,3-butadiene?
a) sp
b) sp²
c) sp³
d) dsp²
Answer: b) sp²
Explanation: In 1,3-butadiene, each carbon atom involved in the double bond is sp² hybridized, leading to planar geometry.
48. Which of the following is a characteristic of alkynes?
a) They are all gaseous at room temperature.
b) They contain at least one double bond.
c) They are unsaturated hydrocarbons.
d) They are more stable than alkenes.
Answer: c) They are unsaturated hydrocarbons.
Explanation: Alkynes are classified as unsaturated hydrocarbons because they contain at least one triple bond between carbon atoms.
49. Which of the following compounds cannot undergo oxidation to form a ketone?
a) Propan-2-ol
b) Butan-2-ol
c) Ethanol
d) 2-Pentanone
Answer: c) Ethanol
Explanation: Ethanol can be oxidized to form acetaldehyde but cannot be oxidized to form a ketone since it is a primary alcohol.
50. Which of the following compounds will produce a yellow precipitate when treated with iodine?
a) 1-Butyne
b) Benzene
c) Ethanol
d) Cyclopropane
Answer: a) 1-Butyne
Explanation: 1-Butyne will produce a yellow precipitate of iodoform (CHI₃) when treated with iodine and sodium hydroxide, indicating the presence of a terminal alkyne.
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