Question

1. Salt can be recovered from its solution by evaporation. Suggest some other technique
for the same

2. Which of the following fall in the category of pure substance.
Milk, wood. Hydrochloric acid, air, pond water, gold, ice cream, sodium, Copper sulphate

3. An unknown compound 'A 'is on thermal decomposition produce 'B' and 'C. What is A? An
element, compound or a mixture?

4. Identify element from the following substances.
Sulphur. Brine, Hydrochloric acid, water, Neon, paper, sugar.

5. Classify the following as pure substance and mixture.
Air, coin, steel, Iron, gasoline, milk, diamond, distilled water, oxygen,
22carats Gold, iodized table salt.
sodium chloride.

6. Classify the following into element, compound and mixtures.
Pure sand, air, Ammonia gas, ice, glass, Calcium oxide, Arsenic oxide.

7. Identify suspension, colloid and true solution from the following.
Pond water, fog, sand in water, aluminum paint, alcohol and water, vinegar, oil in water, glucose
solution, mist, automobile exhaust, Potassium permanganate in water, shaving cream.

8. Classify metals, non-metals and metalloid from the following.
Germanium, Boron, Diamond, Iodine, Copper, Helium

9. If a beam of light is passed through a solution, the beam of light gets illuminated, then the solution is
true solution, transparent solution, homogeneous solution, colloidal solution.
someone help plz​

Answer 1

Answer:

1...Evaporation works the same way as distillation, just at a slower rate. Pour the salt water into a shallow pan. As the water evaporates, the salt will remain behind. You can speed up the process by raising the temperature or by blowing dry air over the surface of the liquid.

Answer 2

Answer:

1)Crystallisation' is a better technique than 'evaporation' because it removes soluble impurities also, which do not get removed in the process of evaporation.

Explanation:

2)Ice, iron, hydrochloric acid, calcium oxide, mercury are pure substances as they have definite composition. Milk is a colloid and acts as a heterogeneous mixture hence is not a pure substance.

3)An unknown substance 'A' on thermal decomposition produces 'B' and 'C'. What is 'A'—an element, a compound or a mixture? Answer: Unknown substance 'A' should be a compound because elements and mixture do not decompose