DF Multiple Choice Questions

Question 1

Which molecule is a structural isomer of E-but-2-ene?

• Z-but-2-ene
• 2-methylbut-2-ene
• methylpropane
• methylpropene

Answer 1

• methylpropene

Question 2

Which statement must be true for an exothermic reaction?

• More bonds are broken than are made
• More bonds are made than are broken
• More energy is released in breaking bonds than is required to make bonds
• More energy is released in making bonds than is required to break bonds

Answer 2

• More energy is released in making bonds than is required to break bonds

Question 3

Which reaction would have a negative value for ΔH?

• CaCO_3(s) –> CaO_(s) + CO_2(g)
• CaO_(s) + H2O_(l) –> Ca(OH)_2(s)
• 2H₂O_(l) –> 2H_2(g) + O_2(g)
• K_(g) –> K⁺_(g) + e^–

Answer 3

• CaO_(s) + H2O_(l) –> Ca(OH)_2(s)

Question 4

What amount of gas takes up 6 dm³ at 102 kPa and 25 °C?

• 0.247 mol
• 2.94 mol
• 4.05 mol
• 247 mol

Answer 4

• 0.247 mol

Question 5

Which statement is true of the first step in the mechanism of the reaction between ethene and hydrogen bromide?

• The bromine atom accepts an electron pair from the carbon–carbon double bond.
• The sigma bond between the two carbon atoms is broken.
• A bromide ion is formed.
• A carbon atom becomes negatively charged.

Answer 5

• A bromide ion is formed.

Question 6

Which of these is an advantage of using biodiesel as a substitute for petrol?

• It is a renewable resource
• No CO₂ is released on combustion
• It has a higher energy density
• Less NO_x is released on combustion

Answer 6

• It is a renewable resource

Question 7

The alkenes are an example of a homologous series of compounds.

Which statement is true for all members of any homologous series?

• They all have the same molecular formula.
• They all have the same general formula.
• They all have the same physical properties.
• They all react with bromine water.

Answer 7

• They all have the same general formula.

Question 8

A Hess cycle is shown below.

What is a correct expression for ΔH₁ constructed using the Hess cycle shown?

• Δ_fH(C₂H₅OH) – [Δ_fH(CH₂CH₂) + Δ_fH(H₂O)]
• [Δ_fH(CH₂CH₂) + Δ_fH(H₂O)] – Δ_fH(C₂H₅OH)
• Δ_cH(CH₂CH₂) – Δ_cH(C₂H₅OH)
• Δ_cH(C₂H₅OH) – Δ_cH(CH₂CH₂)

Answer 8

• Δ_cH(CH₂CH₂) – Δ_cH(C₂H₅OH)

Question 9

What is the correct name for the compound shown below?

• Z-but-2-ene
• E-1-methyl-2-ethylethene
• Z-1-methyl-2-ethylethene
• Z-pent-2-ene

Answer 9

• Z-pent-2-ene

Question 10

Three flasks each contain 240 cm³ of a different gas, under the same conditions of room temperature and pressure.

Which of the following statements is/are true for all three of the flasks?

1. They each contain the same number of gas molecules.
2. They each contain 0.1 mol of gas.
3. They each contain the same number of atoms.

• 1,2, and 3
• Only 1 and 2
• Only 2 and 3
• Only 1

Answer 10

• Only 1