Catalyst

Q.

Why is cooking of food a chemical change?

Q.

Sliced apples turn brown after some time. What is the reason for this? Which type of change is this? What kind of change is cutting of apples? [2 MARKS]

Q.

6. What happens when an incense stick is burned?

Q.

What is the catalyst used for the decomposition of potassium chlorate into potassium chloride and oxygen at a lower temperature?

1. Manganese dioxide

2. Manganese oxide

3. Manganese chloride

4. Manganese chlorate

Q.

What is needed for photosynthesis in which carbon dioxide and water react in the presence of chlorophyll to produce glucose and oxygen?

1. Close contact

2. Light

3. Solution form

4. Catalyst

Q.

Curdling of milk is an example of

1. Slow change

2. Desirable change

3. Irreversible change

4. All of these

Q.

7. Which new materials are formed when a candle burns?

Q. The total number of products formed by thermal decomposition of $\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2$ are :

1. 3

Q.

Burning of coal is a______change.

Q. [TBQVII.(4)]
What type of change is artificial ripening of fruit?

Q.

Refer to the image of a freshly baked cake.

(a) Is baking a physical or chemical change?

(b) Is it a reversible or irreversible change?

(c) Is baking an endothermic or exothermic change?

Q.

Burning is a chemical change that can be reversed.

1. True
2. False

Q.

State whether a chemical change is reversible or irreversible.

Q.

6. Match the columns:

Column 1	Column 2
heat evolved	slow change
burning of fuel	chemical change
new substance formed	periodic change
growth of plant	endothermic
beating of heart	fast change

Q.

A __ is a substance which changes the rate of a chemical reaction without itself undergoing any chemical change.

Q. write a chemical equation to show the change that occurs when magnesium ribbon is burnt in air. name the product formed and mention the characteristics of the flame produced

Q.

Burning of coal is a ______________ change.

Q.

Why is the germination of a seed a chemical change?

Q.

What is needed for photosynthesis in which carbon dioxide and water react in the presence of chlorophyll to produce glucose and oxygen?

1. Close contact

2. Solution form

3. Light

4. Catalyst

Q.

chemical equations of how sewage enters water

Q. [TBQVII.(4)]
What type of change is artificial ripening of fruit?

Q.

Which element is commonly used in catalytic converters due to its property of a reducing agent?

1. At

2. O

3. Pt

4. Cs