INTRODUCTION TO ORGANIC CHEMISTRY [dchemlc]

What are hydrocarbons made up of?

• hydrogen

• carbon

• chlorine

• oxygen

Answer explanation

The simplest organic compounds are hydrocarbons. These are molecules that contain carbon and hydrogen only.

Which of the following molecular formulae can not give the empirical formula CH₄?

• C₂H₆

• C₃H₈

• C₄H₁₀

• C₅H₁₄

Answer explanation

C₅H₁₄ does not have an empirical formula.

Structural isomers are molecules with the

• same molecular formula, but different structural formulae.

• Same molecular formula and same structural formulae

• Different molecular formula, but same structural formulae

• Different molecular formula and different structural formulae

Answer explanation

Structural isomers are molecules with the same molecular formula, but different structural formulae.

what kind of reactions do alkenes undergo?

• addition

• substitution

• dehydration

• neutralization

Answer explanation

In an addition reaction something is added to a molecule without taking anything away. Alkenes undergo addition reactions.

Which of the following statements are not true for a homologous series of compounds?

• They have similar chemical properties

• They have the same molecular formula

• They have the same functional group

• They have the same general formula

Answer explanation

A homologous series is a series of compounds with similar chemical properties because they have the same functional group. Each member differs from the next by one -CH₂-.

What will be produced by the combustion of pent-2-ene?

• Carbon dioxide

• Hydrogen

• Water

• Carbon

• oxygen

Answer explanation

Combustion of hydrocarbons in excess oxygen gives rise to carbon dioxide and water, together with the release of a large amount of heat energy.

Which of the following structural formulae do not represent butane? 

• 
• 
• 
• 

Answer explanation

Each structure (except the answer) shows four carbon atoms joined together in a chain, but the chain has simply twisted. This happens in real molecules as well: the atoms can rotate around single carbon-carbon bonds.

What is the name of the given compound?

• 2,3-dimethylpent-2-ene

• 3-ethyl-2-methylbut-2-ene

• 2,3-dimethylpentene

• 2-methylpent-2-ene

Which of the following is not an isomer of C₅H₁₀?

• 
• 
• 
• 

Answer explanation

this structure is named 2-methylpropane

give the structural formula of 2-methylpropane

Answer explanation