Question

Multiple choice questions MCQ choose the correct answer for each of the following.
1. crystallization is a process of obtaining
a. pure solids only.
b. pure liquids only.
c. pure gas only.
d. all of these.

2. observe the following two changes change A: Biogas is produced by decomposition of animal and plant waste by aerobic bacteria. Change B: biogas is burnt as other fuels. which of these is a chemical change?
a. change A
b. change B
c. both a and b
d. none of these

3. rusting of iron can be prevented by
a. galvanizing
b. electroplating
c. alloying
d. all of these


4. LPG ( liquefied petroleum gas) is used as fuel in kitchen. it exist as a liquid in a cylinder. when it comes out of the cylinder, it becomes a gas (change A). it is burnt to produce heat energy (change B). which of the following statement is correct?
a. change A is a physical change and change B is a chemical change.
b. change A is a chemical change and change B is a physical change.
c. both changes A and B are physical change
d. both changes A and B are chemical change

5. when an iron nail is dipped in blue copper sulphate solution,
i. colour of the solution changes to green.
ii. colour of the solution fades.
iii. brown deposit is observed on the iron nail.
iv. brown deposit is observed at the bottom of the beaker.

which of the above statements are correct?
a. i and ii are correct
b. i and iii are correct
c. ii and iv are correct
d. I and iv are correct

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Answer 1

Explanation:

1. A
2. C
3. D
4. A
5. C

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Answer 2

Answer:

1. pure solids only

2. both a and b

3. all of these

4. change A is physical and change b is chemical

5. ii and iv are correct

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