GCSE AQA AI C9.4 Cracking and Alkenes (Cognito)

What is crude oil primarily made up of?

• Pure alkanes

• Saturated alcohols

• A mixture of hydrocarbons

• Carbon dioxide and water

What process is used to separate crude oil into its component hydrocarbons?

• Cracking

• Filtration

• Electrolysis

• Fractional distillation

Which type of hydrocarbon makes the best fuels?

• Long-chain hydrocarbons

• Short-chain hydrocarbons

• Alkenes only

• Aromatic hydrocarbons

What is the main purpose of cracking hydrocarbons?

• To make crude oil more viscous

• To remove impurities

• To produce shorter, more useful hydrocarbons

• To separate oil from water

What type of reaction is cracking?

• Polymerization

• Combustion

• Neutralization

• Thermal decomposition

In catalytic cracking, what catalyst is commonly used?

• Copper sulfate

• Iron oxide

• Aluminium oxide

• Zinc carbonate

What is required for steam cracking?

• Cold temperatures and high pressure

• Water and low heat

• Mixing hydrocarbon vapour with steam and heating to a high temperature

• Adding a metal catalyst at room temperature

What is a key difference between alkanes and alkenes?

• Alkanes are unsaturated, alkenes are saturated

• Alkenes have double bonds, alkanes have single bonds

• Alkenes contain oxygen, alkanes do not

• Alkanes turn bromine water colourless

What is the chemical test for alkenes?

• They form a white precipitate with silver nitrate

• They turn red litmus paper blue

• They decolorize bromine water from orange to colorless

• They produce a pop sound with a lit splint

What happens to the total number of carbon and hydrogen atoms in a balanced cracking reaction?

• They increase

• They decrease

• They stay the same

• Only hydrogen increases