Question

1. You are provided with a mixture of naphthalene and ammonium chloride by your teacher. Suggest an activity to separate them with well labelled diagram.
2. It is a hot summer day, Priyanshi and Ali are wearing cotton and nylon clothes respectively. Who do you think would be more comfortable and why?
3. You want to wear your favourite shirt to a party, but the problem is that it is still wet after a wash. What steps would you take to dry it faster?
4. Comment on the following statements:
(a) Evaporation produces cooling.
(b) Rate of evaporation of an aqueous solution decreases with increase in
humidity.
(c) Sponge though compressible is a solid.

5. Why does the temperature of a substance remain constant during its melting point or boiling point?
6. Fractional distillation is suitable for separation of miscible liquids with a boiling point difference of about 25 K or less. What part of fractional distillation apparatus makes it efficient and possess an advantage over a
simple distillation process. Explain using a diagram.





7. Iron filings and sulphur were mixed together and divided into two parts, ‘A’ and ‘B’. Part ‘A’ was heated strongly while Part ‘B’ was not heated. Dilute hydrochloric acid was added to both the Parts and evolution of gas was seen in both the cases. How will you identify the gases evolved?
8. A child wanted to separate the mixture of dyes constituting a sample of ink. He marked a line by the ink on the filter paper and placed the filter paper in a glass containing water as shown in figure .
The filter paper was removed when the water moved near the top of the filter paper.
(i) What would you expect to see, if the ink contains three different
coloured components?
(ii) Name the technique used by the child.
(iii) Suggest one more application of this technique.

9. A group of students took an old shoe box
and covered it with a black paper from all
sides. They fixed a source of light (a torch)
at one end of the box by making a hole in it
and made another hole on the other side to
view the light. They placed a milk sample
contained in a beaker/tumbler in the box
as shown in the Fig.2.4. They were amazed
to see that milk taken in the tumbler was illuminated. They tried the same activity by taking a salt solution but found
that light simply passed through it?
(a) Explain why the milk sample was illuminated. Name the phenomenon
involved.
(b) Same results were not observed with a salt solution. Explain.
(c) Can you suggest two more solutions which would show the same effect
as shown by the milk solution?

10. Classify each of the following, as a physical or a chemical change. Give
reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change in the colour of black tea on adding lemon juice to it.
(e) Churning of milk cream to get butter.

Answer 1

Answer:

1) ammonium chloride being sublime can be removed from the mixture by heating up (putting the mixture in a beaker under a Bunsen burner)

2) Priyanshi will feel more comfortable because cotton clothes have natural fibres which have pores and allow evaporation of sweat

3)to dry it faster ,we can hang it under the sun or keep it under a fan

4)yaar itna sawal kon karta hai..jitna jawab di hu..uska points do aur brainliest answer mark karo..thik h K

.

.or Thora padh bhi Liya karo itna sawal nhi puchte h brainly me ek saat

Answer 2

Answer:

No ans

Explanation:

Thanks