Class 7 Science - Chapter Physical and Chemical Changes NCERT Solutions | Fill in the blanks in the following stat
Fill in the blanks in the following statements:
(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.
(b) The chemical name of baking soda is _________.
(c) Two methods by which rusting of iron can be prevented are _________ and _________.
(d) Changes in which only _________ properties of a substance change re called physical changes.
(e) Changes in which new substances are formed are called _________ changes.
(a) Calcium carbonate (CaCO3)
CO2 that is Carbon dioxide reacts with Ca(OH)2 (Calcium hydroxide) that is lime water, to form a white precipitate of CaCO3 (Calcium carbonate).
(b) Sodium hydrogen carbonate
The chemical name of baking soda is (NaHCO3) Sodium hydrogen carbonate (Sodium bicarbonate) .Sodium bicarbonate comes with sodium, acid and hydrogen. Sodium carbonate is diprotic and a strong base compound.
(c) Painting and galvanization Metals which cannot wear easily are melted into their molten form and are used to cover metals which rust easily. The surface of iron or metal are coated with paint or grease. Galvanization is the process of applying a protective layer of zinc on a metal. It is a very common method of preventing the rusting of iron.
(d) Physical
The change in which physical properties of the substance or a material change, this is called physical change. In physical changes, no new substances are formed.
(e) Chemical
The changes in which cannot be seen by naked eyes are called chemical changes. The chemical changes cannot be reversed.
More Questions From Class 7 Science - Chapter Physical and Chemical Changes
- Q:-
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food - Q:-
Describe how crystals of copper sulphate are prepared.
- Q:-
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
- Q:-
State whether the following statements are true or false. In case a statement is false, write the corrected statement in your notebook.
(a) Cutting a log of wood into pieces is a chemical change. (True/False)
(b) Formation of manure from leaves is a physical change. (True/False) (c) Iron pipes coated with zinc do not get rusted easily. (True/False)
(d) Iron and rust are the same substances. (True/False)
(e) Condensation of steam is not a chemical change. (True/False) - Q:-
Explain how painting of an iron gate prevents it from rusting.
- Q:-
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
- Q:-
How would you show that setting of curd is a chemical change?
- Q:-
The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exist as a liquid. When it comes out from the cylinder it
becomes a gas (Change – A) then it burns (Change – B). The following statements pertain to these changes. Choose the correct one.(i) Process – A is a chemical change.
(ii) Process – B is a chemical change.
(iii) Both processes A and B are chemical changes.
(iv) None of these processes is a chemical change. - Q:-
Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.
- Q:-
Explain why rusting of iron objects is faster in coastal areas than in deserts.
Popular Questions of Class 7 Science
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State similarities and differences between the laboratory thermometer and the clinical thermometer.
- Q:-
State differences between acids and bases.
- Q:-
Name the elements that determine the weather of a place.
- Q:-
Fill the missing word in the blank spaces in the following statements:
(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of ——— pressure to a region of ———. - Q:-
In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants - Q:-
Why does an athlete breathe faster and deeper than usual after finishing the race?
- Q:-
Match structures given in Column I with functions given in Column II.
Column I Column II
(i) Stomata (a) Absorption of water
(ii) Xylem (b) Transpiration
(iii) Root hairs (c) Transport of food
(iv) Phloem (d) Transport of water
(e) Synthesis of carbohydrates - Q:-
Fill in the blanks:
(a) Production of new individuals from the vegetative part of parent is called_____________.
(b) A flower may have either male or female reproductive parts. Such a flower is called_____________.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as _____________.
(d) The fusion of male and female gametes is termed as _____________.
(e) Seed dispersal takes place by means of _____________, _____________ and _____________. - Q:-
Classify the following as motion along a straight line, circular or oscillatory motion:
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge. - Q:-
Why do organisms need to take food?
Recently Viewed Questions of Class 7 Science
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State two experiences that made you think that air exerts pressure (other than those given in the text).
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You have been asked to maintain a garden. How will you minimise the use of water?
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Explain what you understand by sexual reproduction.
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A wooden spoon is dipped in a cup of ice cream. Its other end
(a) becomes cold by the process of conduction.
(b) becomes cold by the process of convection.
(c) becomes cold by the process of radiation.
(d) does not become cold. - Q:-
Mark ëTí if the statement is true and ëFí if it is false:
(i) During heavy exercise the breathing rate of a person slows down. (T/F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
(iv) The fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F) - Q:-
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
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What is sludge? Explain how it is treated.
- Q:-
Match the items given in Column I with one or more items of Column II.
Column I Column II
(a) A plane mirror (i) Used as a magnifying glass.
(b) A convex mirror (ii) Can form image of objects spread over a large area.
(c) A convex lens (iii) Used by dentists to see enlarged image of teeth.
(d) A concave mirror (iv) The image is always inverted and magnified. (e) A concave lens (v) The image is erect and of the same size as the object.
(vi) The image is erect and smaller in size than the object. - Q:-
State two differences between a convex and a concave lens.
- Q:-
One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be
(a) 80°C (b) more than 50°C but less than 80°C
(c) 20°C (d) between 30°C and 50°C
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