Physical and Chemical Changes Class 7 Quiz Question with Answer
Physical and Chemical Changes Class 7 Quiz Question with Answer. CBSE Class 7 Science Lesson 6 Mock Test.
Multiple choice questions
1.) New substance is formed in _______.
a) physical change
b) chemical change
c) Temporary change
d) none of these
Answer: – b) chemical change
Explanation: – New substances are formed due to chemical change and are permanent. New substances cannot be formed in physical changes.
2) Choose physical change from the following –
a) boiling water
b) cooking a rice
c) rusting of iron
d) none of there
Answer :- a) Boiling water
Explanation: – Boiling water is a physical change, in which no new substance is formed during boiling of water while cooking rice or rusting of iron is chemical change.
3.) Which of the following is a chemical change?
a) digestion of food
b) cooking of food
c) both a and b
d) None of these.
Answer: – c) both a and b
Explanation: – Both digestion of food and cooking of food is a chemical change because digestion is the process in which food molecules break down into simple from complex and is a permanent change the same goes with cooking of food it is a permanent change.
4.) In which of the following process salt is obtained by the evaporation of sea water?
a) galvanization
b) crystallization
c) transpiration
d) all of these
Answer:- b) crystallization
Explanation :-b) Crystallization is a process of obtaining salt by the evaporation of seawater
5) Salt is obtained by the evaporation of _____________.
a) lack water
b) sea water
c) ground water
d) none of these
Answer: – b) sea water
Explanation: – The Seawater evaporates due to the Sun’s heat and solid salt is left behind. The remaining salt is collected and refined to get purified salt. Thus, salt is obtained from sea water by evaporation.
6) Rusting of iron is which of the following change?
a) physical change
b) chemical change
c) both a and b
d) none of these
Answer: – b) chemical
Explanation: – Rusting of iron is a chemical change where iron reacts with air moisture to form Iron Oxide which is known as rust.
7) Which of the metal is used to prevent rusting among the following?
a) copper
b) zinc
c) Aluminum
d) iron
Answer: – b) zinc
Explanation: – Metals are coated with zinc to prevent them from rusting. This process is called Galvanization.
8) Which of the following changes occurs while formation of curd from milk?
a) chemical change
b) physical change
c) temporary change
d) none of these
Answer: – a) chemical change
Explanation: – Formation of curd from milk is a chemical change because curd cannot be reversed back into milk i.e. is a permanent change.
9) Chemical formula of rust is?
a) Fe 2
b) Fe 2 o 3
c) Fe 3o 3
d) Fe 2 O 4
Answer:- b) Fe2O 3
Explanation: – Rust is Iron oxide formed via chemical change in iron on reaction air in presence of moisture. Chemical formula for Rust i.e. Iron Oxide is Fe2O3 .
10) Select the incorrect statement among the following.
a) The cooking of any food is a chemical change
b) formation of curd from milk is physical change
c) formation of clouds is a reversible change
d) Burning is a chemical change.
Answer :- b) formation of curd from milk is physical change
Explanation: – Formation of curd from milk is chemical change and not physical change because after the formation of curd, it cannot be reversed into milk so it is chemical change.
11.) find odd one out :
Melting of ice, burning of wood, cooking any food, milk becoming curd
a) melting of ice
b) burning of wood
c) cooking of any food
d) milk becoming of curd
Answer: – a) melting of ice
Explanation: – melting of ice is a reversible change (Physical change) while burning of wood, cooking of any food and milk becoming curd are non-reversible changes ( chemical change ).
12) Which is the chemical name of lime water among the following?
a) copper sulphate
b) ferric oxide
c) calcium hydroxide
d) None of these
Answer:- c) calcium hydroxide
Explanation: – Limewater is known as calcium hydroxide and have chemical formula Ca(0H)2.
12) What is the molecular formula of vinegar?
a) (CacoH 2)
b) ( NaHco 3 )
c) (CH 3 CooH )
d) (Fe2O 3 )
Answer :- c) (CH 3COOH)
Explanation: – CH 3 COOH is a molecular formula of vinegar and vinegar contains acetic acid.
13) Which of the following statement is correct?
a) Salt is obtained by evaporation
b) New substance is formed in physical change
c) Rust is formed in the absence of air.
d) Cutting of wood is a chemical change.
Answer: – a) Salt is obtained by evaporation.
Explanation: – Formation of salt occurs via Evaporation of Sea water. New substances are formed in a Chemical change not Physical Change. Rust is Iron Oxide formed in the presence of air. Cutting of wood is a physical change. Hence, option a) is correct.
14) Choose the incorrect pair among the following?
a) melting of wax – Physical change
b) Boiling of water – chemical change
c) crystallization – large crystal formed
d) lime water – (Ca(0H)2 )
Answer:- b) boiling of water – chemical change
Explanation: – all the pair is correct except only ( boiling of water – chemical change) boiling of water is a physical change it does not change its properties and it can be reversed back to its original state so, the correct option is b .
15) Deposition of zinc layer on iron is termed as which of the following?
a) crystallization
b) galvanization
c) painting
d) none of these
Answer :- b) galvanization
Explanation :- Galvanization is the process of coating a zinc layer on iron to prevent rusting. While, crystallization is the process of formation of large crystals of pure substance.
16) Molecular formula of baking soda is ___________.
a) CH3 CooH
b) NaHCo3
c) Fe2O3
d) CuSo4
Answer:- b) NaHCO3
Explanation :- Sodium Bicarbonate is commonly known as Baking Soda. NaHCO 3 is a molecular formula of baking soda.
17) A bud tarring into flower is termed as which of the following?
a) chemical change
b) temporary change
c) physical change
d) none of these
Answer:- a) chemical change
Explanation: – Bud tarring into flower is a chemical change, Bud changes its properties and develops into flower. Flower cannot be reversed back into bud and thus it is Chemical change.
18) Carbon dioxide is passed through lime water then it changes into which substance?
a) limewater turns milky
b) lime motor does not change
c) lime Water turn into black
d) none of these
Answer:- a) limewater turns into milky.
Explanation: – When Carbon dioxide passes through lime water it reacts and forms calcium carbonate, formation calcium carbonate makes limewater milky.