Physical And Chemical Changes(CLASS VII)
Q.1
Fill in the blanks :
1.
Photosynthesis is a _______________ change.
2.
The micro-organisms which convert the dead plants and animals to humus are known as ______________.
3.
The freezing point is ____0C at which water freezes.
4.
Lactobacillus bacterium helps in the formation of ______________.
5.
Galvanization is the process of coating iron objects with the layer of ________ metal.
Q.2
Correct the following sentences by replacing the highlighted words :
1.
Change in the physical properties of a substance is termed as chemical change.
Ans.
______________________________________________________________
2. Boiling is the process in which water
turns to ice when cold enough (below 00C temperature.)
Ans.
______________________________________________________________
3.
Formation of new substances by change in one or more substances is called physical change.
Ans.
______________________________________________________________
4.
The process of deposition of brownish layer on iron when it is exposed to air
and water is
called polishing.
Ans.
______________________________________________________________
5.
Melting is the process of formation
of solid crystals from solution.
Ans.
______________________________________________________________
MCQ’S
1. Melting of ice is a
a. Chemical change b. Physical change c. Periodic change d.
Both physical and chemical change
2. Which of these is the smallest particle?
a. An atom b. A molecule c. A speck of dust d. A water drop
3. Formation of a compound is
a. Physical change b. Temporary change c. Chemical change d.
Reversible change
4. Sea water is a
a. Element b. Compound c. Mixture d. Molecule
7. Match the following
Column A Column B
a. Burning of candle
i. Mixture
b. Tearing of paper ii. Compound
c. Burning petrol iii. Physical change
d. Water iv. Chemical change
e. Air
v. Both physical and chemical
change
8 Fill in the blanks
a. Burning of magnesium is a ------------------ change.
b. The changes that occur in chemical reactions are
------------.
c. Matter is classified as element, compound and
---------------.
d. Chemical name of NaCO3 is -------------------.
e. In chemical reaction reactants changes into
----------------.
9. Cooking of food is a chemical change . Why?.
10 Why water is a compound but air is a mixture?
11. What is crystallization? Give it uses in daily life.
12. Classify as physical and chemical changes
a. Melting of ice
b. Formation of water
c. Tearing of paper
d. Ripening of fruit
e. Formation of curd from milk
f. Stitching of cloth
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