Soil — Science STD 7 — Question

Which part/ parts of a tree is/ are helpful in purifying air?

Melting of wax is a change where a solid changes to liquid state. Give one more such change which you observe in your surroundings.

Some, plants have red, brown and violet pigment. Do these leaves carry out photosynthesis?

Plants prepare their food using a different mode of nutrition than us. What is it?

Fill in the blanks with the appropriate answers:

The process of water seepage into the ground is called ________.

How do you prepare lime water?

Name one place where hollow bricks are used.

How does exchange of gases take place in unicellular and smaller multicellular animals?

Name the most common device which is used to measure the time.

Predict the following change can be reversed or not be reversed. If you are not sure, you may write that down. Why are you not sure about these?
Grinding wheat grains to flour