Secondary School (English Medium) (5 to 8) कक्षा ७ - CBSE Question Bank Solutions for Science

Then and now: Talk to your grandparents and other elderly people in the neighbourhood. Find out the sewage disposal systems available to them. You can also write letters to people living in far off places to get more information. Prepare a brief report on the information you collected.

Visit a sewage treatment plant.

It could be as exciting and enriching as a visit to a zoo, a museum, or a park. To guide your observation here are a few suggestions.

Record in your notepad:

Place ______ Date ______ Time ______

Name of the official at the plant ______ Guide/Teacher ______

1. The location of the sewage plant.
2. Treatment capacity.
3. The purpose of screening as the initial process.
4. How is air bubbled through the aeration tank?
5. How safe is the water at the end of the treatment? How is it tested?
6. Where is the water discharged after treatment?
7. What happens to the plant during heavy rains?
8. Is biogas consumed within the plant or sold to other consumers?
9. What happens to the treated sludge?
10. Is there any special effort to protect nearby houses from the plant?
11. Other observations.

You must be familiar with the given nursery rhymes

Baa baa black sheep, have you any wool.

Answer the following:

Which parts of the black sheep have wool?

You must be familiar with the following nursery rhymes:

Mary had a little lamb, whose fleece was white as snow

Answer the following:

What is meant by the white fleece of the lamb?

Which of the following does not yield wool?

What is meant by term Rearing?

What is meant by term Shearing ?

What is meant by term Sericulture?

Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them

Shearing, __________, sorting, __________, __________, __________

Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.

Down

(D) 1: Thorough washing

2 : Animal fibre

3 : Long thread like structure

Across

(A) 1 : Keeps warm

2 : Its leaves are eaten by silkworms

3 : Hatches from egg of moth

Is the distilled water acidic/basic/neutral? How would you verify it?

Sodium hydroxide turns blue litmus red.

Indicator is a substance which shows different colours in acidic and basic solutions. 

Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and the third is a sugar solution. How will you identify them? You have only turmeric indicator.

Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

1. Both acids and bases change colour of all indicators.
2. If an indicator gives a colour change with an acid, it does not give a change with a base.
3. If an indicator changes colour with a base, it does not change colour with an acid.
4. Change of colour in an acid and a base depends on the type of the indicator.

Which of these statements are correct?

Following are some of the characteristics of animals:

Diets heavy on fruits

White fur

Need to migrate

Loud voice

Sticky pads on feet

Layer of fat under skin

Wide and large paws

Bright colours

Strong tails

Long and large beak

For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions?

The tropical rainforest has a large population of animals. Explain why it is so.

Explain, with examples, why we find animals of certain kind living in particular climatic conditions.

How do elephant living in the tropical rainforest adapt itself.