Forests: Our Lifeline — Science STD 7 — Question

You must be familiar with the following nursery rhymes:

1. ‘Baa baa black sheep, have you any wool.’
2. ‘Mary had a little lamb, whose fleece was white as snow.’

Answer the following:

1. Which parts of the black sheep have wool?
2. What is meant by the white fleece of the lamb?

To keep her soup warm Paheli wrapped the container in which it was kept with a woollen cloth. Can she apply the same method to keep a glass of cold drink cool? Give reason for your answer.

We can see objects when the lighted reflected from the objects falls upon our eyes. Why can't walls act as mirror even the light is reflected through walls and reach our eyes?

Why do we often sneeze when we inhale a lot of dust-laden air?

Food moves in the opposite direction during vomiting. How?

What does the hydrangea flower’s colour tell about soil?

Look at the given reaction.
Hydrochloric acid + Sodium hydroxide (base) → Sodium chloride (salt) + Water
Sodium chloride formed in this reaction remains in solution form. Can we get solid sodium chloride from this solution? Suggest a method (if any).

What are indicators? Classify them and give one example of each.

What does the book mean by 'exploration is not just discovery'?

Explain the activity of burning of magnesium ribbon. Represent the change by an equation.