Is Matter Around Us Pure?? Assignment

IMPORTANT MESSAGE FROM THE PRINCIPAL BRO MIRANDA

https://www.youtube.com/watch?v=Nu7x_LMVrAM

Chapter: Is Matter Around Us Pure?

Assignment

1. State the separation technique you would apply for the separation of the following.
(i) Sodium chloride from its solution in water
(b) Oil from water
(iii) iron pins from sand
(iv) Different pigments from an extract of leaves
(v) Butter from curd

2. On dissolving chalk powder in water, a suspension is obtained. Give any two reasons to support the fact that mixture so obtained is a suspension only.

3. Why is blood said to be a mixture whereas oxygen is an element? Mention any reason for each.

4. Give an example of
(a) solid - solid homogeneous mixture.
(ii) liquid - liquid heterogeneous mixture.

5. Identify colloids and true solutions from the following:
Pond water, fog, aluminium paint, vinegar, glucose solution.

6. Give two examples of (i) Aerosol     (ii) Emulsion

7.  Classify the following as chemical or physical changes:
(i) cutting of trees
(ii) melting of butter in a pan
(iii) rusting of almirah
(iv) boiling of water
(v) passing of electric current through water and water breaking down into hydrogen and oxygen gases.
(vi) dissolving common salt in water
(vii) making a fruit salad with raw fruits
(viii) burning of paper and wood

8. A group of students took an old shoe box and covered it will a black paper from all sides. They fixed a sources 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. They placed a 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?

9. 0.5 g of salt is dissolved in 25 g of water. Calculate the percentage amount of the salt in the solution.      (Check your answer 1.96%)

10. Non-metals are usually poor conductors of heat and electricity. They are non-lustrous, non-sonorous, non-malleable and are coloured.

(a) name a lustrous non-metal.
(b) name a non-metal which exists as a liquid at room temperature.
(c) a non-metal is a good conductor of electricity.(Allotropic form of carbon)
(d) a non-metal which is known to form the largest number of compounds.
(e) a non-metal which is required for combustion.