Calculate the mass of sodium sulphate required to prepare its 20% (mass percent) solution in 100g of water?

How much water should be mixed with 12 ml of alcohol so as to obtain 12% alcohol solution?

A 15% alcohol solution means:

(a) 15 ml alcohol and 85 ml water.

(b) 15 ml alcohol and 100 ml water.

Choose the correct answer.

What do you understand by the statement “the solubility of copper sulphate in water at 20°C is 20.7 g’?

(a) Differentiate between a saturated and an unsaturated solution. How will you test whether a given solution is saturated or not?

Calculate the concentration of a solution which contains 2.5 g of salt dissolved in 50 g of water.

When the solid A is added to water, it dissolves with the evolution of a lot of heat and making little explosions to form two products B and C. The properties of products B and C are entirely different from those of solid A as well as water. Moreover, products B and C cannot be reconverted into solid A and water. When another solid D is added to water, it dissolves with the absorption of a little heat to form a product E which cools down. The product E shows the properties of both, solid D as well as water. Moreover, product E can be converted into solid D and water.

(a) What type of change occurs when solid A is dissolved in water? Why?

(b) What type of change occurs when sold D is dissolved in water? Why?

(c) Name a metal which you think could behave like solid A. Also name the products B and C.

(d) Name the solid D if it is the one which is used in making ordinary dry cells.

(e) Name the process by which D can be recovered from E.

Tincture of iodine has antiseptic properties. This solution is made by dissolving:

Which one of the following is not a chemical change?

Which of the following represents the solubility of sugar in water at 20°C?