Q1) Change - is the law of nature that occurs in everyday life.
State when a substance (i.e. matter) undergoes a kind of change.
Q2) Give a reason why
(a) Freezing of water is a reversible change while burning of a candle - an irreversible change.
(b) Change of seasons is a periodic change while a change of weather is non-periodic change.
Q3) State which of the following pertain to - chemical changes.
(a) Substance retains its identity.
(b) The change is permanent.
(c) No new substance is formed.
(d) Is easily reversible.
(e) Produces one or more new substances by a change in its composition.
(f) The change is temporary.
(g) The composition and properties of the original substance are not altered.
Q4) Give four reasons why the burning of a magnesium ribbon in the air is considered a chemical change.
Q7) State which of the following terms connected with change of state of matter i.e.
(a) Melting (b) Vaporization (c) Condensation (d) Freezing pertain to -
Conversion of liquid into vapour or gas.
Conversion of liquid into solid.
Conversion of solid into a liquid on heating.
Q8) Potassium Chloride is added to water and stirred. A salt solution is obtained which is then boiled leaving behind a residue.
(a) Is the above change physical or chemical change?
(b) Name the residue which remains behind after the salt solution is boiled.
(c) Is the change reversible or not reversible?
(d) Are the composition and properties of the original substance altered.
(e) Give a reason why the above experimentation would not be possible if calcium carbonate is taken in place of potassium chloride.
Q9) Give a reason why -
(a) Heating a platinum wire is a reversible change but, heating a magnesium wire is an irreversible change.
(b) The addition of zinc nitrate to water is a physical change but addition of zinc to dilute nitric acid is a chemical change.
(c) Rusting of iron is a chemical change but the magnetization of iron is a physical change.
Q10) Select the chemical changes from the following list of changes.
(a) Vaporisation of water into water vapour
(b) Boiling of milk
(c) Respiration in mammals
(d) Rotting of eggs
(e) Drying of a fruit
(f) The carbon cycle
(g) Occurrence of lightning
(h) Breaking of glass
(i) Butter turning rancid
(j) Glowing of an electric bulb
(k) Crystallization of salt from its solution
(l) Change of seasons
(m) Preparation of carbon dioxide from calcium carbonate & dilute hydrochloric acid.
Q1) Select the correct answer from the choice in bracket to complete each sentence
A change in which a substance retains its identity is a ______ [[physical/chemical]] change.
Matter is added or removed during a ______ [[physical/chemical]] change.
Energy required for completion of a physical change is _______ [[released/absorbed] when the change is reversed.
Dissolution of lead nitrate in water is deemed as a ______ [[physical/chemical]] change.
A change in which matter undergoes a change but the total mass of substance is unaltered is a _________ [[physical/chemical]] change.
Q2) State which of the following 1 to 5 pertain to - A: Physical Change B: Chemical Change
Q5) Name the following.
The salt obtained when a chemical change takes place on the addition of iron to dilute sulphuric acid.
The product obtained during a physical change when water converts from a liquid into a solid.
The product of the chemical change is keeping a polished iron nail exposed to the atmosphere.
A form of energy required for a chemical change.
The gaseous product of the chemical change which takes place during respiration in living organisms.
Q3) Give reasons why the following are considered as chemical changes.
Q4) Match the examples of changes in List I with the correct type of changes in List II
|List I||List II|
|1. Burning of paper||A: Physical Change|
|2. The ringing of an electric bell||B: Chemical Change|
|3. Curdling of milk|
|4. Electric light is switched on|
|5. Melting of butter|
Terms & Policies
Terms & Policies