NCERT Solutions for Chapter: Is Matter Around Us Pure?, Exercise 3: Long Answer Questions

Classify drying of a shirt in the sun, as a physical or a chemical change. Give reason.

Classify the rising of hot air over a radiator, as a physical or a chemical change. Give reason.

Classify burning of kerosene in a lantern, as a physical or a chemical change. Give reason.

Classify change in the colour of the black tea on adding lemon juice to it, as a physical or a chemical change. Give reason.

Classify churning of milk cream to get butter, as a physical or a chemical change. Give reason.

During an experiment the students were asked to prepare a $10\%$ (Mass/Mass) solution of sugar in water. Ramesh dissolved $10 \mathrm{g}$ of sugar in $100 \mathrm{g}$ of water while Sarika prepared it by dissolving $10 \mathrm{g}$ of sugar in water to make $100 \mathrm{g}$ of the solution.
Are the two solutions of the same concentration?

During an experiment the students were asked to prepare a $10\%$ (Mass/Mass) solution of sugar in water. Ramesh dissolved $10 g$ of sugar in $100 g$ of water while Sarika prepared it by dissolving $10 g$ of sugar in water to make $100\mathrm{g}$ of the solution.
Compare the mass % of the two solutions.

Arun has prepared $0.01\%$ (by mass) solution of sodium chloride in water. Which of the following correctly represents the composition of the solutions?