During an experiment the students were asked to prepare a 10% (Mass/Mass)
solution of sugar in water. Ramesh dissolved 10g of sugar in 100g of water
while Sarika prepared it by dissolving 10g of sugar in water to make 100g
of the solution.
(a) Are the two solutions of the same concentration
(b) Compare the mass % of the two solutions.
Classify each of the following, as a physical or a chemical change. Give
reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change in the colour of black tea on adding lemon juice to it.
(e) Churning of milk cream to get butter.
Iron filings and sulphur were mixed together and divided into two parts,
‘A’ and ‘B’. Part ‘A’ was heated strongly while Part ‘B’ was not heated. Dilute
hydrochloric acid was added to both the Parts and evolution of gas was
seen in both the cases. How will you identify the gases evolved?
(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?
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 makes it efficient and possess an advantage over a
simple distillation process. Explain using a diagram.
Which of the following are not compounds?
(a) Chlorine gas
(b) Potassium chloride
(c) Iron
(d) Iron sulphide
(e) Aluminium
(f) Iodine
(g) Carbon
(h) Carbon monoxide
(i) Sulphur powder
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) The allotropic form of a non-metal is a good conductor of electricity.
Name the allotrope.
(d) Name a non-metal which is known to form the largest number of
compounds.
(e) Name a non-metal other than carbon which shows allotropy.
(f) Name a non-metal which is required for combustion.
On heating calcium carbonate gets converted into calcium oxide and carbon
dioxide.
(a) Is this a physical or a chemical change?
(b) Can you prepare one acidic and one basic solution by using the
products formed in the above process? If so, write the chemical equation
involved.
Can we separate alcohol dissolved in water by using a separating funnel?
If yes, then describe the procedure. If not, explain.
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