Q97. An element is sonorous and highly ductile. Under which category would you classify this element? What other characteristics do you expect the element to possess? ‘

 

Q98. 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.

 

Q99. How can we obtain pure copper sulphate from an impure sample?

 

Q100. What is a suspension? Write its properties.

Or

What are the properties of suspension?

 

Q101. What is the principle of centrifugation write its application?

 

Q102. How can we obtain coloured component (dye) from blue/black ink? 

 

Q103. How can we separate a mixture of two immiscible liquids?

Or

How will you separate a mixture of kerosene oil and water?

 

Q104. Name the process associated with the following:

(a) Dry ice is kept at room temperature and at one atmospheric pressure.

(b) A drop of ink placed on the surface of water contained in a glass spreads throughout the water.

(c) A potassium permanganate crystal is in a beaker and water is poured into the beaker with stirring.

(d) An acetone bottle is left open and the bottle becomes empty.

(e) Milk is churned to separate cream from it.

(f) Settling of sand when a mixture of sand and water is left undisturbed for some time.

(g) Fine beam of light entering through a small hole in a dark room, illuminates the particles in its paths.

 

Q105. What do you mean by solute and solvent? Explain with the help of examples.

 

Q106. Classify the following as chemical or physical changes:

• cutting of trees,

• melting of butter in a pan,

• rusting of almirah,

• boiling of water to form steam,

• passing of electric current, through water and the water breaking down into hydrogen and oxygen gases,

• dissolving common salt in water,

• making a fruit salad with raw fruits, and

• burning of paper and wood.

 

Last modified: Wednesday, 5 May 2021, 12:27 PM