Secondary School (English Medium) (5 to 8) Class 7 - CBSE Question Bank Solutions for Science

What are decomposers?

The main steps of nutrition in humans are ______, ______, ______, ______ and ______.

Match the items of Column I with those given in Column II:

Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?

Name the source from which litmus solution is obtained. What is the use of this solution?

Nitric acid turns red litmus blue.

Tooth decay is caused by the presence of a base.

Dorji has a few bottles of soft drink in his restaurant. But, unfortunately, these are not labelled. He has to serve the drinks on the demand of customers. One customer wants acidic drink, another wants basic and third one wants neutral drink. How will Dorji decide which drink is to be served to whom?

Classify the changes involved in the following process as physical or chemical changes:

Photosynthesis

State whether the following statement is true or false. In case a statement is false, write the corrected statement.

Cutting a log of wood into pieces is a chemical change.

Changes in which only ______ properties of a substance change are called physical changes.

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

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

What are the components of blood?

What makes the blood look red?

Explain how animals dwelling in the forest help it grow and regenerate.

Explain how forests prevent floods.

What do decomposers do in the forest?

Explain the role of forest in maintaining the balance between oxygen and carbon dioxide in the atmosphere.

Explain why there is no waste in a forest.