Mixtures and Compounds NDA Questions

NDA Chemistry

Mixtures and Compounds MCQ Questions


1.
Matter is classified into 'pure substances' and 'mixtures'. Pure substances are further classified as:
A.
Metals and Non-metals
B.
Elements and Compounds
C.
Solutions and Suspensions
D.
Homogeneous and Heterogeneous mixtures
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ANSWER :
B. Elements and Compounds
2.
Which of the following NCERT examples are correctly classified as COMPOUNDS?
A.
Water (H₂O), Common salt (NaCl), Calcium carbonate (CaCO₃), Methane (CH₄), Carbon dioxide (CO₂)
B.
Air, Soil, Blood, Sugar solution
C.
Iron, Oxygen, Sodium, Silicon
D.
Milk, Foam, Smoke, Fog
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ANSWER :
A. Water (H₂O), Common salt (NaCl), Calcium carbonate (CaCO₃), Methane (CH₄), Carbon dioxide (CO₂)
3.
Why is a mixture different from a compound in terms of composition?
A.
A mixture can contain only one element; a compound must contain at least three
B.
A mixture shows no properties of its components; a compound shows combined properties
C.
A mixture can be made in any ratio of its components; a compound always has a fixed, definite ratio of its elements by mass
D.
A mixture is always a liquid; a compound is always a solid
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ANSWER :
C. A mixture can be made in any ratio of its components; a compound always has a fixed, definite ratio of its elements by mass
4.
Which of the following is a key characteristic that separates a compound from its constituent elements?
A.
A compound has completely different properties from its constituent elements (e.g., water is a liquid while H₂ and O₂ are gases)
B.
A compound always occurs as a gas at room temperature
C.
A compound always conducts electricity while its elements do not
D.
A compound always has a higher melting point than its elements
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ANSWER :
A. A compound has completely different properties from its constituent elements (e.g., water is a liquid while H₂ and O₂ are gases)
5.
The properties of a mixture, compared to a pure substance, are:
A.
A mixture has a completely new set of properties unlike any of its components
B.
A mixture has exactly the same properties as the compound formed from the same components
C.
A mixture always shows different properties from all its components
D.
The properties of a mixture are the combined properties of its constituent substances, each retaining its original chemical properties
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ANSWER :
D. The properties of a mixture are the combined properties of its constituent substances, each retaining its original chemical properties
6.
Iron filings and sulphur powder are mixed. Some of this mixture is heated with a magnet held over it. What are the results?
A.
Before heating: no effect; After heating: magnet attracts the black product
B.
Before heating: magnet attracts the iron filings (mixture — each component retains its property). After heating (compound FeS forms): magnet does NOT attract the black solid because FeS is a compound with new properties
C.
Before heating: sulphur burns; After heating: iron becomes magnetic
D.
Before and after heating: magnet attracts the material equally
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ANSWER :
B. Before heating: magnet attracts the iron filings (mixture — each component retains its property). After heating (compound FeS forms): magnet does NOT attract the black solid because FeS is a compound with new properties