NYGH - Organic Chemistry (Alkanes and Alkenes)

Which of the following about crude oil is true?

• It can be separated into pure alkanes by fractional distillation.

• Crude oil is a mixture consisting mainly of alkenes.

• Fractions are separated by their boiling points.

• Paraffin is used as a raw material for making plastics and detergents.

Which of the following about natural gas is NOT true?

• Natural gas is also known as petroleum gas.

• Natural gas is 90% methane by volume.

• Natural gas is a source of alkanes.

• Natural gas contains propane gas.

(a)   hydrocarbons contain at least one double covalent bond between two adjacent carbon atoms somewhere in the molecule.

Which of the following is an alkane?

• C₅H₁₀

• C₆H₆

• C₂H₂

• C₇H₁₆

Which of the following is an alkene?

• C₉H₁₂

• C₄H₆

• C₁₄H₂₈

• C₁₀H₂₂

Which of the following trends in physical properties are true for alkanes with increasing molecular mass?

(You can select more than 1.)

• Melting and boiling points decrease.

• Density decreases.

• Viscosity increases.

• Flammability increases.

Which of the following fuels would produce the LEAST smokiest flame when burnt?

• C₂H₄

• C₃H₆

• C₃H₈

• C₄H₁₀

The structure above shows one of the isomers of pentene.

Which of the following is a positional isomer of pentene?

• 
• 
• 
• 

What are the coefficients (a, b, c, d) of the following equation?

a C₈H₁₈ + b O₂ → c CO₂ + d H₂O

• a=2 , b=25/2 , c=8 , d=9

• a=1 , b=25 , c=8 , d=9

• a=2 , b=25 , c=16 , d=18

• a=1 , b=25 , c=16 , d=18

Which of the following is NOT produced from the incomplete combustion of butane?

• carbon

• carbon monoxide

• carbon dioxide

• carbonic acid