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1. Two cubes each of volume 64 cm³ are joined end to end. The surface area of the resulting cuboid is:
A. 160 cm²
B. 128 cm²
C. 144 cm²
D. 120 cm²
Answer: A. 160 cm²
Explanation: Side of cube = ∛64 = 4 cm. For resulting cuboid: l = 8 cm, b = 4 cm, h = 4 cm. Total surface area = 2(lb + bh + hl) = 2(32 + 16 + 32) = 160 cm².
2. Total surface area of a solid hemisphere of radius r is:
A. 2πr²
B. 3πr²
C. 4πr²
D. (2/3)πr³
Answer: B. 3πr²
Explanation: Total surface area of solid hemisphere = Curved surface area + Base area = 2πr² + πr² = 3πr².
3. Curved surface area of a right circular cone with radius r and slant height l is:
A. πr²h
B. πrl
C. 2πrl
D. πr(l + r)
Answer: B. πrl
Explanation: The formula for curved surface area (CSA) of a right circular cone is πrl.
4. Volume of a sphere of radius r is given by:
A. (4/3)πr³
B. (2/3)πr³
C. 4πr²
D. (1/3)πr³
Answer: A. (4/3)πr³
Explanation: Standard formula for the volume of a sphere of radius r is (4/3)πr³.
5. If the radius of a sphere is doubled, then its volume becomes how many times?
A. 2 times
B. 4 times
C. 8 times
D. 16 times
Answer: C. 8 times
Explanation: Volume varies with r³. If radius is doubled (2r)³, new volume = 2³ = 8 times original volume.
6. Relationship between height (h), radius (r), and slant height (l) of a cone is:
A. l² = h² + r²
B. l = h + r
C. h² = l² + r²
D. r² = l² + h²
Answer: A. l² = h² + r²
Explanation: By Pythagorean theorem in right-angled triangle formed inside the cone: l = √(r² + h²) ⇒ l² = h² + r².
7. A metallic sphere of radius 3 cm is melted and recast into a wire of radius 0.2 cm. Length of wire is:
A. 900 cm
B. 450 cm
C. 90 cm
D. 360 cm
Answer: A. 900 cm
Explanation: Volume of sphere = Volume of cylinder. (4/3)π(3³) = π(0.2²)h ⇒ 36 = 0.04h ⇒ h = 900 cm.
8. The curved surface area of a cylinder of radius 7 cm and height 10 cm is:
This page contains a chapter-wise objective practice set. Try the questions without checking the answer first, then use the explanation to understand the point you missed. The current page contains 30 questions, so you can practise in smaller sets when you are revising.
Quick revision tip
After the practice set, write down the question numbers you missed and revise only those concepts once more. This makes MCQ practice more useful than repeatedly attempting the same questions without reviewing mistakes.