Chemical Changes

Q.

Magnesium ribbon when burnt in the air forms a new compound. What is the chemical composition of the compound formed and the changes involved in the process?

Q.

Which of the following are examples of chemical reactions?

i. Burning wood

ii. Cutting wood

iii. Conversion of steam to water

iv. Rusting of almirah

v. Dissolving common salt in water

1. i, iv

2. i, iii, v

3. v, ii, iii

4. ii, iv, v

Q.

Which of the below-given process represents a physical change?

1. Rusting of iron

2. Combustion of magnesium ribbon

3. Burning of a candle

4. Melting of wax

Q.

Knitting of wool into a sweater is a ___.

Q.

Which of the following are chemical changes:

(i) Cutting of trees

(ii) Burning of paper

(iii) Boiling of water to form steam

(iv) Rusting of iron almirah

1. (i) and (ii)

2. (i) and (iii)

3. (ii) and (iv)

4. (ii) and (iii)

Q. A substance that changes the rate of a chemical reaction without taking part in it is called as

1. Reactant
2. Product
3. Catalyst
4. Both A & B

Q. Which is not an indicator of chemical reaction?

1. Change in colour
2. Change in state
3. Change in mass
4. Change in temperature

Q.

The heat energy supplied during a physical change is in no way utilised to change the ________ of the molecules of a substance.

Q.

When naphthalene balls are kept inside cotton and woollen clothes in an almirah, the naphthalene balls disappear slowly. Is it a physical change or a chemical change.

Q. Magnesium ribbon when burnt in air forms ash. The chemical composition of the ash formed and the change involved is:

1. Magnesium oxide, physical
2. Magnesium oxide, chemical
3. Magnesium hydroxide, physical
4. Magnesium hydroxide, chemical

Q.

Magnesium ribbon when burnt in the air forms a new compound. What is the chemical composition of the compound formed and the changes involved in the process?

Q.

The changing of ice into water is an example of a-

1. Physical change

2. Chemical change

3. Change of state

4. Both (A) and (C)

Q. Which of the following are examples of chemical reactions?

i. Burning of wood

ii. Cutting of wood

iii. Conversion of steam to water

iv. Rusting of almirah

1. i, iv
2. i, iii
3. ii, iv
4. ii, iii

Q. Which of the following are the examples of a chemical reaction?

1. Conversion of steam to liquid water
2. Rusting of iron
3. Cutting of wood
4. Conversion of paper to paper plane

Q. Which is not an indicator of chemical reaction?

1. Change in colour
2. Change in state
3. Change in mass
4. Change in temperature

Q. Magnesium ribbon when burnt in air forms ash. The chemical composition of the ash formed and the change involved is:

1. Magnesium oxide, physical
2. Magnesium oxide, chemical
3. Magnesium hydroxide, physical
4. Magnesium hydroxide, chemical

Q. Which of the following are the examples of a chemical reaction?

1. Conversion of steam to liquid water
2. Rusting of iron
3. Cutting of wood
4. Conversion of paper to paper plane

Q.

Select the correct answer from the choices A, B, C, and D which are given. Write only the letter corresponding to the correct answer.

Which is an example of chemical change?

1. Water freezes

2. Wood is cut

3. Bread is baked

4. Wire is bent

Q.

Organisms that feed on both plants and animals are ________.