11 Is water an clement or a compound? Give reason in support of your answer.
12. Explain why air is considered as a mixture and not a compound?
13. Suggest separation technique for the following mixtures.
(a) Mercury and water
(b) Potassium chloride and Ammonium chloride
(c) Common salt, water and sand
(d) Kerosenc oil, water and salt
(c) Water and alcohol
..
14. A solution of Urea in water contains 16g of it in 120g of solution. Find out the mass percentage of the
solution.
15. A solution has been prepared by mixing 5.6 ml of alcohol with 75 ml of water.
Calculate the percentage (by volume) of alcohol in the solution.
16. You are given two samples of water labelled as “A” and “B”. Sample A boils at 100°C and B boils at
102°C. Which sample of water will not freeze at 0°C? Comment.
17. The sea water can be classified as a homogeneous as well as heterogeneous mixture. Comment.
18. While diluting a solution of salt in water a student added acetone(B.P 56°C ) by mistake. What
technique can be employed to get back the acetone? Justify your choice.
Plz help i hve exam tmrw
Answers
Answer:
11)Water is a compound because of the following reasons: It is composed of two different elements, hydrogen and oxygen which cannot be separated by physical methods. They can be separated only by electrolysis. The physical and chemical properties of hydrogen and oxygen are entirely different from the properties of water
12)Air is a mixture and not a compound because of following reasons: Air can be separated into its constituents such as oxygen, nitrogen etc. by fractional distillation of liquid air. Air shows the properties of all the gases present in it. For example: Air supports combustion because of oxygen present in air.
13)
14)A solution of urea in water contains 16 grams of it in 120 grams of ... Find put the mass percentage of the solution. 2 ... Mass of solute= 16 g. Mass of solution =120g
15)Total volume of solution = 5.6+75 = 80.6 ml
16)Sample '6' will not freeze at 0°C as, it is impure water. It is because sample 'B' boils at 102°C while the boiling point of pure water is 100°C. It means this sample contains impurities.
17)Sea-water' is called homogeneous as it contains dissolved salts in it. It may be called heterogeneous as it contains various insoluble components too as sand, microbes, shells made of calcium carbonate and so many other things.
18)Distillation can be employed to get back the acetone, since acetone is more volatile it will separate out first. (Distillation is a process that can be used to separate a pure liquid from a mixture of liquid
very sorry I don't know 13th question answer