Question

Q.1 what happens when ice is heated ? Is it a reversible or irreversible change? Justify your answer.

Q.2 what happens when dilute hydrochloric acid is added to zinc metal? Explain.

Q.3 give two example of each of the following changes occurring during a chemical reaction-
A. Change of state of the reactants.
B. Change of colour
C. Evolution of a gas
D. Formation of a precipitate

Q.4 classify the following changes as a physical or a chemical change- Burning of a magnesium ribbon, dissolving sugar in water, burning sugar, melting of butter, breaking of a glass bottle, clothes being ironed, wool being knitted into a sweater, souring of a milk and drawing of wet hair

Q.5 Give reasons for the following-
A. Changing of water into water vapour is considered a physical change.
B. Mixing of sugar with water is considered a reversible change
C. Mixing of cement with water is considered an irreversible change

Q.6 differentiate between the following- A. Fast and slow changes
B. Exothermic and endothermic changes
C. Physical and chemical changes
D. Periodic and non periodic changes
E. Reversible and irreversible changes

Q.7 state whether the following statements are true or false if false rewrite the correct form of statements-
A. Melting of ice is a periodic change
B. Matchstick burns to produce smoke and some gases it is an example of a physical change
C. A chemical change can be used only reversed
D. Formation of alloys is a physical change
E. blackening of surface of silver metal is a chemical change

Q.8. Encircle the odd one out and give reasons for your choice-
A. Souring of milk, inflating a balloon, cooking of food and burning of coal
B. Making of ice cubes, melting of butter, frying of potatoes and heating of water​

Answer 1

reversible. statements-

A. Melting of ice is a periodic change

B. Matchstick burns to produce smoke and some gases it is an example of a physical change

C. A chemical change can be used only reversed

D. Formation of alloys is a physical change

E. blackening of surface of silver metal is a chemical change

Q.8. Encircle