Physical and Chemical Changes NDA Questions

NDA Chemistry

Physical and Chemical Changes MCQ Questions


1.
Which of the following is the correct definition of a 'pure substance'
A.
A liquid that does not contain any dissolved solids
B.
A substance that consists of a single type of particles, all having the same chemical nature, with a fixed composition and definite properties
C.
Any substance found in its natural state without human processing
D.
Any substance that is colourless and odourless
😑 View Answer Rough Work Error
ANSWER :
B. A substance that consists of a single type of particles, all having the same chemical nature, with a fixed composition and definite properties
2.
Which of the following are examples of pure substances?
A.
Smoke, fog, cloud
B.
Milk, air, soil, blood
C.
Sugar solution, sea water, alloy
D.
Gold, silver, water, common salt (sodium chloride), oxygen
😑 View Answer Rough Work Error
ANSWER :
D. Gold, silver, water, common salt (sodium chloride), oxygen
3.
What is a 'mixture' as defined in NCERT Class 9 Chapter 2?
A.
A substance that cannot be separated by physical methods
B.
A substance that has uniform composition throughout
C.
A substance in which components are chemically bonded in fixed proportion
D.
A substance formed when two or more substances are combined in any ratio and each substance retains its own chemical identity
😑 View Answer Rough Work Error
ANSWER :
D. A substance formed when two or more substances are combined in any ratio and each substance retains its own chemical identity
4.
Which of the following statements correctly distinguishes a compound from a mixture?
A.
Compounds are always liquids; mixtures are always solids
B.
In a compound, elements are chemically combined in a fixed ratio; in a mixture, substances are physically combined in any ratio
C.
Compounds can be separated by filtration; mixtures cannot
D.
Compounds are heterogeneous; mixtures are always homogeneous
😑 View Answer Rough Work Error
ANSWER :
B. In a compound, elements are chemically combined in a fixed ratio; in a mixture, substances are physically combined in any ratio
5.
Air is classified as which type of substance?
A.
A pure substance (element)
B.
A compound
C.
A homogeneous mixture
D.
A heterogeneous mixture
😑 View Answer Rough Work Error
ANSWER :
C. A homogeneous mixture
6.
An alloy is classified as which type of material in NCERT Class 9?
A.
A mixture — because alloys can have variable composition and their components retain their individual properties
B.
A pure substance — because alloys have uniform composition throughout
C.
An element — because they are metallic in nature
D.
A compound — because two or more metals are bonded chemically
😑 View Answer Rough Work Error
ANSWER :
A. A mixture — because alloys can have variable composition and their components retain their individual properties