Physical and Chemical Changes NDA Questions

NDA Chemistry

Physical and Chemical Changes MCQ Questions


7.
What is the key difference between a 'homogeneous mixture' and a 'heterogeneous mixture'?
A.
A homogeneous mixture has uniform composition throughout; a heterogeneous mixture has non-uniform composition with physically distinct parts
B.
Homogeneous mixtures can be separated; heterogeneous mixtures cannot
C.
Homogeneous mixtures are compounds; heterogeneous mixtures are elements
D.
Homogeneous mixtures are liquids; heterogeneous mixtures are solids
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ANSWER :
A. A homogeneous mixture has uniform composition throughout; a heterogeneous mixture has non-uniform composition with physically distinct parts
8.
Which of the following correctly defines a 'solution' in chemistry?
A.
A heterogeneous mixture where the solute particles settle down on standing
B.
A mixture where only liquids can be the solvent
C.
Any liquid containing dissolved and undissolved particles
D.
A homogeneous mixture of two or more substances in which the solute is uniformly distributed throughout the solvent
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ANSWER :
D. A homogeneous mixture of two or more substances in which the solute is uniformly distributed throughout the solvent
9.
What is the particle size of solute particles in a true solution?
A.
Between 1 nm and 100 nm
B.
Less than 1 nm (1 nanometre = 10⁻⁹ m)
C.
Between 100 nm and 1000 nm
D.
Greater than 100 nm
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ANSWER :
B. Less than 1 nm (1 nanometre = 10⁻⁹ m)
10.
In a solution, which component is the 'solvent' and which is the 'solute'?
A.
Solvent: the component present in larger quantity that dissolves the other; Solute: the component present in smaller quantity that is dissolved
B.
Solvent: the dissolved component; Solute: the dissolving medium
C.
Solvent: the component that settles down; Solute: the component that remains suspended
D.
Solvent: always a liquid; Solute: always a solid
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ANSWER :
A. Solvent: the component present in larger quantity that dissolves the other; Solute: the component present in smaller quantity that is dissolved
11.
A 'saturated solution' is one in which:
A.
The solution has been heated until all solvent evaporates
B.
The solute and solvent are present in equal quantities
C.
The concentration of solute is exactly 50% by mass
D.
No more solute can be dissolved in the solvent at a given temperature — the solvent has reached its maximum dissolving capacity
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ANSWER :
D. No more solute can be dissolved in the solvent at a given temperature — the solvent has reached its maximum dissolving capacity
12.
The formula for calculating mass percentage concentration of a solution is:
A.
Mass percentage = (Volume of solute / Volume of solution) × 100
B.
Mass percentage = (Mass of solute / Volume of solution) × 100
C.
Mass percentage = (Mass of solute / Mass of solution) × 100
D.
Mass percentage = (Mass of solvent / Mass of solute) × 100
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ANSWER :
C. Mass percentage = (Mass of solute / Mass of solution) × 100