Question

2. Observe the following two changes. Change A: Biogas is produced by decomposition of animal
and plant waste by anaerobic 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 exists 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 changes.
(d) Both changes A and B are chemical changes.
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.
(d) (i) and (iv) are correct.
(c) (ii) and (iv) are correct.​

Answer 1

Answer:

2- BOTH A AND B ARE CHEMICAL CHANGES

3-GALVINIZATION

5- i and iii are correct