chemistry : class12 Density : Physical properties of haloalkanes : Haloalkanes and Haloarenes MCQ Questions and Answers
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Density
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MCQ Questions
1. Which haloalkane generally has a density greater than that of water?
A.
Chloromethane
B.
Bromoethane
C.
Fluoromethane
D.
Chloroethane
Correct Answer:
Bromoethane
Explanation:
Bromoethane contains the relatively heavy bromine atom and has a density greater than that of water, unlike many lower haloalkanes.
2. What is the general effect of replacing chlorine by bromine in a haloalkane molecule on its density?
A.
Density generally increases
B.
Density becomes zero
C.
Density always decreases
D.
Density remains exactly unchanged
Correct Answer:
Density generally increases
Explanation:
Bromine is heavier than chlorine, so replacing chlorine with bromine generally increases the molecular mass and density of the haloalkane.
3. Which of the following haloalkanes is expected to have the highest density because iodine is the halogen present?
A.
Chloromethane
B.
Fluoromethane
C.
Iodomethane
D.
Chloroethane
Correct Answer:
Iodomethane
Explanation:
Iodomethane contains the heaviest halogen among the options, so its density is expected to be the highest.
4. Which statement about the density of many haloalkanes is correct?
A.
They are all gases at room temperature
B.
Their density is unrelated to the halogen atom
C.
Many bromoalkanes and iodoalkanes are denser than water
D.
All haloalkanes are less dense than water
Correct Answer:
Many bromoalkanes and iodoalkanes are denser than water
Explanation:
The presence of the heavier bromine or iodine atom often makes these haloalkanes denser than water.
5. Which halogen substitution generally gives the greatest increase in density of an alkane?
A.
Substitution by fluorine
B.
Substitution by chlorine
C.
Substitution by bromine
D.
Substitution by hydrogen
Correct Answer:
Substitution by bromine
Explanation:
Bromine has a much greater atomic mass than hydrogen and fluorine, so replacing hydrogen with bromine generally produces a larger increase in density.
6. Compared with chloroethane, bromoethane generally has a higher density because it contains:
A.
A lighter halogen atom
B.
A heavier halogen atom
C.
More hydrogen atoms
D.
No halogen atom
Correct Answer:
A heavier halogen atom
Explanation:
Bromoethane contains bromine, which is heavier than chlorine in chloroethane, giving bromoethane a generally higher density.
7. Which property is commonly used to compare whether a liquid haloalkane will lie above or below water?
A.
Density
B.
Colour only
C.
Odour only
D.
Boiling point only
Correct Answer:
Density
Explanation:
A liquid with density greater than water tends to form the lower layer, while a liquid with density less than water tends to form the upper layer.
8. Which of the following is generally the least dense type of haloalkane when the carbon skeleton is similar?
A.
Iodoalkane
B.
Bromoalkane
C.
Chloroalkane
D.
Fluoroalkane
Correct Answer:
Fluoroalkane
Explanation:
Fluorine has the lowest atomic mass among the halogens listed, so fluoroalkanes are generally the least dense for similar carbon skeletons.
9. A haloalkane has a density greater than water. Which observation is most likely when it is mixed with water?
A.
It forms the lower layer
B.
It always dissolves completely
C.
It becomes a gas immediately
D.
It forms the upper layer
Correct Answer:
It forms the lower layer
Explanation:
When two liquids do not mix and one has a greater density than water, the denser liquid settles below water.
10. For haloalkanes with the same carbon chain, which order generally represents increasing density?
Explanation:
For a similar carbon skeleton, density generally increases as the halogen changes from fluorine to chlorine to bromine because the halogen mass increases.
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