GCSE Combined Science Crude oil, fuels & alkenes questions by topic

This question is about crude oil.

1. (a)State the two elements that every hydrocarbon contains.[1]
2. (b)Name the process used to separate crude oil into fractions.[1]
3. (c)State where in the column the shortest-chain fractions condense.[1]
4. (d)Give one reason crude oil should be conserved.[1]

This question is about the alkane family.

1. (a)Write the molecular formula of methane and of ethane.[2]
2. (b)State the general formula of the alkanes.[1]
3. (c)Name the alkane whose molecules contain four carbon atoms.[1]

Complete these combustion sentences and equations.

1. (a)Balance the equation: CH₄ + ___O₂ → CO₂ + 2H₂O.[1]
2. (b)Balance the equation: C₃H₈ + 5O₂ → 3CO₂ + ___H₂O.[1]
3. (c)Name the two products of complete combustion.[1]
4. (d)Name the extra toxic gas made when a fuel burns in too little oxygen.[1]

This question is about how hydrocarbon properties change.

1. (a)State two property changes as hydrocarbon chain length increases.[2]
2. (b)Explain why petrol evaporates easily but bitumen hardly evaporates at all.[2]

This question is about the fractionating column.

1. (a)Describe how the temperature changes from the bottom of the column to the top.[2]
2. (b)Explain why the longest-chain fractions condense at the bottom.[2]
3. (c)Name one fraction and one use of it.[1]

Long alkane molecules are fed over a hot catalyst in a refinery.

1. (a)State the two conditions needed for cracking.[2]
2. (b)Complete the equation: C₁₂H₂₆ → C₁₀H₂₂ + ___.[2]
3. (c)State one reason the alkene product is commercially useful.[1]

Two unlabelled liquids are shaken with orange bromine water. With liquid X the colour disappears; with liquid Y it stays orange.

1. (a)State which liquid is unsaturated.[1]
2. (b)Name the feature of X’s molecules that causes the colour change.[2]
3. (c)Write the general formula of the family X belongs to.[1]
4. (d)State whether Y would give the same result with more bromine water.[1]

This question is about combustion products.

1. (a)Write the balanced symbol equation for the complete combustion of methane, CH₄.[2]
2. (b)A gas flame burns with a yellow, sooty flame instead of blue. Explain what this shows and name the toxic gas that may be forming.[2]
3. (c)Name the pollutant, other than carbon oxides, that contributes to acid rain.[1]

A refinery cracks tetradecane, C₁₄H₃₀, hoping to obtain octane among the products.

1. (a)State the conditions for cracking.[2]
2. (b)One product is octane, C₈H₁₈. The other product is x molecules of C₂H₄. Find x and justify it by counting atoms.[3]
3. (c)Name the family C₂H₄ belongs to and write its general formula.[1]

A delivery company compares petrol from crude oil with biodiesel made from crops.

1. (a)Give two advantages of biodiesel.[2]
2. (b)Give two drawbacks of biodiesel.[2]
3. (c)Suggest why crude-oil fractions still dominate transport fuels.[2]

(Higher) A gas fire in a living room starts receiving too little air through a blocked vent.

1. (a)Name the poisonous gas that may now be produced.[1]
2. (b)Explain how this gas harms the body.[2]
3. (c)Compare the products of the faulty (incomplete) combustion with the complete combustion that should occur.[3]

A student must identify which of two unlabelled liquids is an alkane and which is an alkene.

1. (a)Describe the test the student should carry out.[2]
2. (b)State the result expected for each liquid.[2]