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Weather, Climate and Adaptations of Animals To Climate

Name the elements that determine the weather of a place.

Physical and chemical change

Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.

(i) Process – A is a chemical change.

(ii) Process – B is a chemical change

(iii) Both processes A and B are chemical changes.

(iv) None of these processes is a chemical change.

Physical and chemical change

The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder, it becomes a gas (Change – A) then it burns (Change – B). The following statements pertain to these changes. Choose the correct one.

(i) Process – A is a chemical change.

(ii) Process – B is a chemical change.

(iii) Both processes A and B are chemical changes.

(iv) None of these processes is a chemical change.

Physical and chemical change

Explain why rusting of iron objects is faster in coastal areas than in deserts.

Physical and chemical change

Explain how painting an iron gate prevents it from rusting.

Physical and chemical change

Describe how crystals of copper sulphate are prepared.

Physical and chemical change

Explain why burning wood and cutting it into small pieces are considered two different types of changes.

Physical and chemical change

How would you show that the setting of curd is a chemical change?

Physical and chemical change

When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both chemical and physical changes take place.

Physical and chemical change

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.