Chapter 2 - Is Matter Around Us Pure | Exam Idea Class 9

In a hill station a group of tourists were going for a short tour by a jeep. The driver was repeatedly wiping the glass of front window as there was obstruction of view. Answer the following questions based on the information given above. (i) Why there was obstruction in view? (ii) What precaution should be taken by the driver in the hilly area? (ii) Write any two properties of it.

(𝑖) The obstruction in view was due to formation of a mixture known as smog created by smoke and fog, present in the atmosphere. (𝑖𝑖) The driver should move in…

Anil and Roshan went to a restaurant to have dinner. Anil picked up the glass of water to drink but he immediately kept it back. He said, “The water was not fit for drinking.” Based on the above information answer the questions that follow: (𝒊)What could be the reason of it? (𝒊𝒊) How could have been the water made fit for drinking? Name the process. (𝒊𝒊𝒊) Which values are promoted by the restaurant people here?

(𝑖) Heavy suspended particles might be floating in the water served for drinking. (𝑖𝑖) Water could have been made fit for drinking by adding alum to the water. The heavy…

While chopping vegetables Sushila’s mother accidently injured her fingers due to which she began bleeding profusely. Sushila immediately applied alum on the cut part (wound). The bleeding stopped after some time. (𝒊) Mention the value shown by Sushila in the above case. (𝒊𝒊) What is the role of alum used in the above case?

(𝑖) Presence of mind, knowledgeable. (𝑖𝑖) Alum acts as a coagulant and helps in stopping bleeding.

You are given two samples of water labeled as ‘A’ and ‘B’. Sample ‘A’ boils at 100°C and sample ‘B’ boils at 102oC. Which sample of water will not freeze at 0°c? Comment.

Sample ‘B’ will not freeze at 0°C because it is not pure water. At a atm, the boiling of pure water is 100°C and the freezing point of pure water…

What is the reason foe running cold water through condenser form lower side to upper side in distillation process?

In distillation process condensation of vapors take place. To absorb more heat, cold water is passed from lower side so that it will stay for longer time and absorb more…

Can we separate alcohol dissolved in water by using a separating funnel? If yes, then describe the procedure. If not, explain.

We cannot separate alcohol dissolved in water by using separating funnel because both the components are highly soluble in each other. They can be separate by fractional distillation.

There student A, B and C prepared mixture using chalk powder, common salt and milk respectively in water. Whose mixture: (i) would not leave reside on filter paper after filtration? (ii) would show Tyndall effect? (iii) would give transparent/clear solution? (iv) would settle down at the bottom when left undisturbed? (v) could be filtered by filter paper?

(i) (a) Mixture of common salt and water. (b) Mixture of milk and water. (ii) Mixture of chalk powder with water and milk with water (iii) Mixture of common salt…

Explain why filter paper cannot be used to separate colloids.

The size of colloidal particles is less then 1nm, while the size of pores present in an ordinary filter paper is large than 1nm. Hence, a colloidal solution cannot be…

The teacher instructed three students ‘A’ ‘B’ and ‘C’ respectively to prepare a 50% (mass by volume) solution of sodium hydroxide (NaOH). ‘A’ dissolved 50 g of NaOH in 100 mL of water to make 100 mL of solution. Which one of them has made the desired solution and why?

‘C’ has made the desired solution because 50% (mass by volume) solution means 50 g of solute dissolved in 100 mL of solution. Mass by volume per cent = 𝑀𝑎𝑠𝑠…

(a) Under which category of mixtures will you classify alloys and why? (b) A solution is always a liquid. Comment. (c) Can a solution be heterogeneous?

(a) Alloys are homogeneous mixture of two or more elements because the constituent elements mix together and give a mixture which uniform together. (b) No, solid solutions and gaseous solutions…

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