Which raw material is separated by fractional distillation to obtain useful fuels such as petrol and diesel?
Crude oil
Limestone
Iron ore
Sea water
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WhyCrude oil is a mixture of hydrocarbons that is separated into fractions by fractional distillation, providing fuels like petrol and diesel.
2Multiple choice · Easy
What is the general formula of the alkanes?
CnH2n+2
CnH2n
CnH2n-2
CnHn
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WhyAlkanes are saturated hydrocarbons with the general formula CnH2n+2, for example methane CH4 (n=1).
3Multiple choice · Easy
Which test is used to distinguish an alkene from an alkane?
Adding aqueous bromine and observing decolourisation
Adding limewater and observing it turning milky
Adding damp blue litmus paper
Heating with copper(II) oxide
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WhyAlkenes are unsaturated and rapidly decolourise aqueous bromine; alkanes are saturated and do not, so the bromine test distinguishes them.
4Multiple choice · Easy
What is the name of the functional group present in alcohols?
Hydroxyl (-OH)
Carboxyl (-COOH)
Carbon-carbon double bond (C=C)
Carbonyl (C=O)
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WhyAlcohols contain the hydroxyl group, written as -OH, which gives the homologous series its characteristic properties.
5Multiple choice · Easy
Which compound is the second member of the alkene homologous series?
Propene, C3H6
Ethene, C2H4
Propane, C3H8
Butane, C4H10
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WhyThe alkenes start at C2H4 (ethene); the second member is propene, C3H6, with the general formula CnH2n.
6Fill in the blank · Easy
A series of compounds with the same general formula and similar chemical properties is called a series.
Answer:
homologous
WhyA homologous series is a family of compounds with the same general formula, similar chemical properties and a gradual change in physical properties.
7Multiple choice · Medium
Fractions near the top of the fractionating column compared with fractions near the bottom have:
Lower boiling points and shorter carbon chains
Higher boiling points and longer carbon chains
Higher viscosity and lower flammability
Larger molecules that flow less easily
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WhySmaller molecules condense higher up where it is cooler; they have lower boiling points, are more volatile, more flammable and less viscous.
8Multiple choice · Medium
Which equation represents the complete combustion of methane?
CH4 + 2O2 -> CO2 + 2H2O
CH4 + O2 -> CO2 + H2O
CH4 + 2O2 -> 2CO + 2H2O
2CH4 + 3O2 -> 2CO2 + 4H2
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WhyComplete combustion of a hydrocarbon in excess oxygen gives only carbon dioxide and water: CH4 + 2O2 -> CO2 + 2H2O.
9Multiple choice · Medium
Ethanol can be manufactured by fermentation. Which conditions are required?
Glucose and yeast, around 30 degrees C, no air
Glucose and a nickel catalyst at 200 degrees C
Ethene and steam with a catalyst at high pressure
Crude oil heated with concentrated sulfuric acid
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WhyFermentation uses glucose (from sugars) with yeast at about 25-35 degrees C in the absence of air (anaerobic), producing ethanol and carbon dioxide.
10Multiple choice · Medium
Which functional group is responsible for the acidic properties of carboxylic acids?
-COOH
-OH
-C=C-
-COO-
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WhyCarboxylic acids contain the carboxyl group -COOH, which can release a hydrogen ion in water, making solutions weakly acidic.
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