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Chemistry · Question 111
Which gas forms at the cathode during electrolysis of aqueous sodium chloride with inert electrodes?
Oxygen
Hydrogen
Nitrogen
Chlorine
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Correct answer: B
Hydrogen
Water is reduced at the cathode, releasing hydrogen. Molten sodium chloride behaves differently.
Chemistry · Question 112
What name is given to the Group 1 metals of the periodic table?
Noble gases
Alkali metals
Halogens
Alkaline earth metals
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Correct answer: B
Alkali metals
Group 1 metals are the alkali metals; Group 2 metals are alkaline earth metals.
Chemistry · Question 113
Which halogen is liquid at approximately 25 degrees C and atmospheric pressure?
Iodine
Fluorine
Chlorine
Bromine
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Correct answer: D
Bromine
Bromine is liquid under these conditions; fluorine and chlorine are gases, and iodine is solid.
Chemistry · Question 114
Which noble gas can be used to inflate weather balloons?
Argon
Helium
Xenon
Krypton
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Correct answer: B
Helium
Helium is a light, nonflammable noble gas suitable for lifting balloons.
Chemistry · Question 115
Which functional group characterises an alcohol?
-CHO
-OH attached to a saturated carbon
-COO-
-COOH
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Correct answer: B
-OH attached to a saturated carbon
Alcohols have a hydroxyl group bonded to a saturated carbon atom.
Chemistry · Question 116
What is the general molecular formula of an acyclic alkene containing one carbon-carbon double bond?
CnH2n-2
CnHn
CnH2n+2
CnH2n
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Correct answer: D
CnH2n
One double bond reduces the hydrogen count by two compared with the corresponding acyclic alkane.
Chemistry · Question 117
What is the IUPAC name of CH3CHO?
Propanone
Ethanol
Ethanoic acid
Ethanal
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Correct answer: D
Ethanal
CH3CHO is the two-carbon aldehyde ethanal. Ethanol is CH3CH2OH.
Chemistry · Question 118
Which of these compounds is aromatic?
Ethane
Ethene
Cyclohexane
Benzene
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Correct answer: D
Benzene
Benzene has a cyclic conjugated system containing six delocalised pi electrons.
Chemistry · Question 119
What is the main organic product when ethanol is heated under reflux with excess acidified potassium dichromate(VI)?
Ethene
Ethanoic acid
Methanol
Ethane
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Correct answer: B
Ethanoic acid
Under these conditions, the primary alcohol is oxidised through ethanal to ethanoic acid.
Chemistry · Question 120
Which compound gives a positive Tollens' test under standard test conditions?
Propanone
Ethene
Ethanal
Ethane
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Correct answer: C
Ethanal
Ethanal is an aldehyde and reduces Tollens' reagent to metallic silver.