,Question 1
Dodecane is an alkane.
,The general formula for alkanes is:
CₙH₂ₙ₊₂
What is the molecular formula of dodecane?
A. C₁₂H₂₄
B. C₁₂H₂₆
C. C₁₂H₂₈
D. C₁₂H₂₂
Correct Answer: B
Rationale:
For an alkane:
H = 2n + 2
For n = 12:
H = (2 × 12) + 2 = 26
Therefore, the formula is C₁₂H₂₆.
Question 2
A student investigates the viscosity of dodecane at different temperatures.
Which statement correctly describes viscosity?
A. The resistance of a liquid to flow
B. The temperature at which a liquid boils
C. The density of a liquid
D. The amount of liquid flowing through a container
Correct Answer: A
Rationale:
Viscosity is a measure of how strongly a liquid resists flowing. A liquid with high viscosity
flows less easily than a liquid with low viscosity.
Question 3
The student heats dodecane before allowing it to flow through the hole.
What is expected to happen to the viscosity of dodecane as temperature increases?
, A. It increases
B. It decreases
C. It remains exactly constant
D. It becomes zero
Correct Answer: B
Rationale:
For a liquid, increasing temperature generally reduces viscosity. The particles have greater
kinetic energy and can move past one another more easily.
Question 4
The student collects 64 cm³ of dodecane in 40 seconds.
What is the mean flow rate?
A. 0.625 cm³/s
B. 1.6 cm³/s
C. 24 cm³/s
D. 160 cm³/s
Correct Answer: B
Rationale:
Mean flow rate = volume ÷ time
64 ÷ 40 = 1.6 cm³/s
Question 5
At a higher temperature, 80 cm³ of dodecane flows through the apparatus in 40 seconds.
At a lower temperature, 50 cm³ flows through in the same time.
Which conclusion is best supported?
A. Dodecane is more viscous at the higher temperature.
B. Dodecane is less viscous at the higher temperature.
C. Temperature has no effect on viscosity.
D. Dodecane changes into an alkene at the higher temperature.
Correct Answer: B
Dodecane is an alkane.
,The general formula for alkanes is:
CₙH₂ₙ₊₂
What is the molecular formula of dodecane?
A. C₁₂H₂₄
B. C₁₂H₂₆
C. C₁₂H₂₈
D. C₁₂H₂₂
Correct Answer: B
Rationale:
For an alkane:
H = 2n + 2
For n = 12:
H = (2 × 12) + 2 = 26
Therefore, the formula is C₁₂H₂₆.
Question 2
A student investigates the viscosity of dodecane at different temperatures.
Which statement correctly describes viscosity?
A. The resistance of a liquid to flow
B. The temperature at which a liquid boils
C. The density of a liquid
D. The amount of liquid flowing through a container
Correct Answer: A
Rationale:
Viscosity is a measure of how strongly a liquid resists flowing. A liquid with high viscosity
flows less easily than a liquid with low viscosity.
Question 3
The student heats dodecane before allowing it to flow through the hole.
What is expected to happen to the viscosity of dodecane as temperature increases?
, A. It increases
B. It decreases
C. It remains exactly constant
D. It becomes zero
Correct Answer: B
Rationale:
For a liquid, increasing temperature generally reduces viscosity. The particles have greater
kinetic energy and can move past one another more easily.
Question 4
The student collects 64 cm³ of dodecane in 40 seconds.
What is the mean flow rate?
A. 0.625 cm³/s
B. 1.6 cm³/s
C. 24 cm³/s
D. 160 cm³/s
Correct Answer: B
Rationale:
Mean flow rate = volume ÷ time
64 ÷ 40 = 1.6 cm³/s
Question 5
At a higher temperature, 80 cm³ of dodecane flows through the apparatus in 40 seconds.
At a lower temperature, 50 cm³ flows through in the same time.
Which conclusion is best supported?
A. Dodecane is more viscous at the higher temperature.
B. Dodecane is less viscous at the higher temperature.
C. Temperature has no effect on viscosity.
D. Dodecane changes into an alkene at the higher temperature.
Correct Answer: B
