10 questions🇬🇧English
🧪 Alkenes & Electrophilic Addition – A-level
Chemistry · A-level — practises E/Z isomerism, addition mechanisms, carbocation stability and polymers
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Questions
Which description correctly matches the bonding in a C=C double bond?
One σ bond and one π bond
Two σ bonds
One σ bond and two π bonds
Two π bonds
20s
Bromine water is shaken with an alkene. What colour change is seen?
Colourless to orange
Orange to colourless
Purple to colourless
Orange to green
20s
Which of these alkenes shows E/Z isomerism?
But-1-ene
Propene
But-2-ene
2-methylpropene
20s
Which is the repeat unit of poly(propene)?
–CH₂–CH₂–
–CH₂–CH(CH₃)–
–CH₂–CH₂–CH₂–
–CH₂–C(CH₃)₂–
30s
What is the major product when propene reacts with hydrogen bromide?
Propan-2-ol
2-bromopropane
1,2-dibromopropane
1-bromopropane
30s
In the mechanism of ethene with HBr, the first curly arrow starts at the C=C bond. Where does it point?
To a carbon atom in the alkene
To the H atom of HBr
To a lone pair on Br
To the Br atom of HBr
30s
Why is a tertiary carbocation more stable than a primary carbocation?
More alkyl groups push electron density onto C⁺
The tertiary C⁺ has a full outer shell
Alkyl groups withdraw electrons from C⁺
Fewer alkyl groups crowd the C⁺
30s
Br₂ is a non-polar molecule. How can it act as an electrophile towards an alkene?
The C=C electron density induces a dipole in Br₂
Br₂ is permanently polar like HBr
Br₂ splits into Br radicals in the dark
The alkene donates a proton to Br₂
30s
Propene reacts with cold concentrated H₂SO₄ and the product is then warmed with water. What is the major organic product?
Propyl hydrogensulfate
Propan-2-ol
Propane-1,2-diol
Propan-1-ol
30s
In one isomer of 2-chlorobut-2-ene, CH₃C(Cl)=CHCH₃, both CH₃ groups are on the same side of the C=C. What is it?
The Z isomer
The E isomer
It has no E/Z isomers
A racemic mixture
60s