CLASS IX
ASSINGMENT-CHEMISTRY IS MATTER AROUND US PURE
Q1. Based on which factor a solution is said to be dilute, concentrated or saturated?
Q2. “Tyndall Effect can be observed when sunlight passes through the canopy of
dense forest.” Explain how this occurs.
Q3. Choose the elements, mixture and compound from: (i) Brass (ii) Diamond (iii)
Sand.
Q4. Classify each of the following as element, compound or mixture: Gold, Air,
Marble, milk, sugar.
Q5. How can we obtain different gases from air?
Q6. Which of the two will scatter light: soap solution or salt solution?
Q7. Salt can be recovered from its solution by evaporation can you suggest any other
technique also?
Q8. You are provided with solution of substance ‘X’. How will you test whether it is
saturated or unsaturated with respect to ‘X’ at a given temperature? What happens
when a hot saturated solution is allowed to cool?
Q9. What would you observe when(a) a saturated solution of potassium chloride prepared at 60oC is allowed to cool at
room temperature?
(b) an aqueous sugar solution is heated to dryness ?
(C) a mixture of iron filings and sulphur powder is heated strongly?
Q10. Why blood is a mixture and graphite is an element? Mention any one reason for
each.
Q11. What is tincture of iodine? Identify solute and solvent in ‘tincture of iodine.’.
Why Tyndall effect is not seen in true solution?
Q12. Why it is possible to distinguish the particles of solute from those of solvent in a
suspension?
Q13. Sidak took 50ml of water in two beakers at room temperature and added
sodium chloride to one beaker while sugar to the other, till no more solute would be
dissolved. Then she heated the contents of the beakers and added more solutes in
them.
(a) Will the amount of salt and sugar that can be dissolved in water at given
temperature same?
(b) What will you expect to happen if she cools the contents of the beakers? Justify
your answer.
Q14. Enumerate any two differences between simple distillation and fractional
distillation.
Q15. Identify homogeneous mixtures from the following. (i) smoke (ii) Brass (iii)
Tincture of iodine (iv) Milk
Q16. Write the role of following in water purification system:
(a) Sedimentation tank
(b) Loading tank
(c) chlorination tank
Q17. 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 100mL of water, ‘B’ dissolved 50 g of NaOH in 100 g water while ‘C’ dissolved
50 g of NaOH in water to make 100 mL of solution. Which one of them has made the
desired solution and why?
Q18. Identify the dispersed phase and dispersing medium in the following colloids:
(a) Fog (b) Cheese (c) Coloured gemstone
Q19. Suggest separation technique one would need to employ to separate the
following mixtures:
(a) Mercury and water.
(b) Potassium chloride and ammonium chloride.
(c) Common salt, water and sand.
(d) Kerosene oil, water and salt.
Q20. The ‘sea-water’ can be classified as a homogeneous as well as heterogeneous
mixture. Comment.
Q21. Sucrose (sugar) crystals obtained from sugarcane and beetroot are mixed
together. Will it be a pure substance or a mixture? Give reasons for the same.
Q22. 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
make it efficient and possess an advantage over a simple distillation process. Explain
using a diagram.
Q23. (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?
Q24. Why cream separates from milk on churning?
Q25. What is the different between aqueous and non-aqueous solution?
Q26. Crystallisation method is used to get salt from sea water. Why is it so?