General Questions
Practice and master this topic with our carefully crafted questions.
The perimeter of one face of a cube is 20 cm. Its volume must be :
Correct Answer: A. 125 cm³ ✅
- A. 125 cm³ ✅ — Correct.
- B. 400 cm³ ❌
- C. 1000 cm³ ❌
- D. 8000 cm³ ❌
Explanation:
A face of a cube is a square.
Perimeter of one face = 20 cm.
Side of the square = 20 ÷ 4 = 5 cm.
Volume of cube = side³
= 5³
= 125 cm³.
Exam Fact:
For a cube, Volume = side³. The perimeter of one face is 4 × side.
Therefore, the correct answer is A. 125 cm³ ✅.
A rectangular water tank is 80 m × 40 m. Water flows into it though a pipe 40 Sq. cm at the opening at a speed of 10 Km/Hr. By how much, the water level will rise in the tank in half an hour ?
Correct Answer: C. 5/8 cm ✅
- A. 3/2 cm ❌
- B. 4/9 cm ❌
- C. 5/8 cm ✅ — Correct.
- D. None of these ❌
Explanation:
Dimensions of the tank = 80 m × 40 m.
Area of tank base = 80 × 40 = 3200 m².
Area of pipe opening = 40 cm² = 40/10,000 = 0.004 m².
Speed of water = 10 km/hr = 10,000 m/hr.
Volume of water flowing in 1 hour:
= 0.004 × 10,000 = 40 m³.
In half an hour:
Volume = 40 × 1/2 = 20 m³.
Let the rise in water level be h metres.
Volume = Area of tank × height
20 = 3200 × h
h = 20/3200 = 0.00625 m.
Converting to centimetres:
0.00625 × 100 = 0.625 cm = 5/8 cm.
Exam Fact:
For water tanks, use Volume = Base Area × Rise in Water Level. Also remember to convert all units to the same system before calculating.
Therefore, the correct answer is C. 5/8 cm ✅.
50 men took a dip in a water tank 40 m long and 20 m broad on a religious day. If the average displacement of water by a man is 4 m³, then the rise in the water lavel in the tank will be:
Correct Answer: B. 25 cm ✅
- A. 20 cm ❌
- B. 25 cm ✅ — Correct.
- C. 35 cm ❌
- D. 50 cm ❌
Explanation:
Number of men = 50.
Displacement by each man = 4 m³.
Total volume of displaced water = 50 × 4 = 200 m³.
Base area of the tank = 40 × 20 = 800 m².
Let the rise in water level be h metres.
Volume displaced = Base area × Rise
200 = 800 × h
h = 200/800 = 0.25 m.
Converting into centimetres:
0.25 × 100 = 25 cm.
Exam Fact:
Rise in water level = Volume displaced ÷ Base area of tank.
Therefore, the correct answer is B. 25 cm ✅.
2(15 + 12) x h = 2(15 x 12)
h = |
180 | m = | 20 | m. |
| 27 | 3 |
Volume = |
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15 x 12 x | 20 | m3 |
= 1200 m3. |
| 3 |
External radius = 4 cm,
Internal radius = 3 cm.
| Volume of iron |
|
||||||
|
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| = 462 cm3. |
Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.
Clearly, l = (48 - 16)m = 32 m,
b = (36 -16)m = 20 m,
h = 8 m.
Volume of the box = (32 x 20 x 8) m3 = 5120 m3.
| Volume of water displaced | = (3 x 2 x 0.01) m3 |
| = 0.06 m3. |
Mass of man
| = Volume of water displaced x Density of water | |
| = (0.06 x 1000) kg | |
| = 60 kg. |
Let the length of the wire be h.
| Radius = | 1 | mm | = | 1 | cm. | Then, |
| 2 | 20 |
|
22 | x | 1 | x | 1 | x h = 66. |
| 7 | 20 | 20 |
h = |
![]() |
66 x 20 x 20 x 7 | ![]() |
= 8400 cm = 84 m. |
| 22 |
1 hectare = 10,000 m2
So, Area = (1.5 x 10000) m2 = 15000 m2.
| Depth = | 5 | m | = | 1 | m. |
| 100 | 20 |
Volume = (Area x Depth) = |
![]() |
15000 x | 1 | m3 |
|
| 20 |
Area of the wet surface:
| = [2(lb + bh + lh) - lb] | |
| = 2(bh + lh) + lb | |
| = [2 (4 x 1.25 + 6 x 1.25) + 6 x 4] m2 | |
| = 49 m2. |
h =
m3