 General Knowledge Quiz (Previous Years) for NDA & Other Defence Exams: 12th April

Dear Students, Defence Adda is providing you all with this quiz on General Knowledge questions for NDA & Other Defence Exams.

Q1. Why doesn’t Archimedes’ principle hold for a vessel under a free fall?
(a) The effective value of g increases
(b) The effective value of g decreases
(c) The density of air increases
(d) The body immersed in the vessel will become weightless

Q2. A block of weight W floats in a lake. If the apparent weight of the floating block is W’, then which one of the following in correct?
(a) W’ > W
(b) W, = W/2
(c) W ‘= W
(d) W’ = 0

Q3. The specific gravity of a substance is measured by a hydrometer at the sea level. If the measurement is done at the top of a mountain, what would be the specific gravity?
(a) Zero
(b) More than that measured at the sea level
(c) Less than that measured at the sea level
(d) Same as that measured at the sea level

Q4. Consider the following statement:
If there were no capillarity,
1. it would be impossible to use a kerosene lamp.
2. one would not be able to use a straw to consume a soft drink.
3. the blotting paper would fail to function.
4. there would have been no plants on the earth.
Which of the statements given above are correct?
(a) 1, 2 and 4
(b) 1, 3, 4
(c) 2, 3
(d) 1, 2, 3, 4

Q5. A solid cube of iron (specific gravity = 8) is melted into sheets. The side of the cube is 1m. The sheets are used to make a hollow cube. Floats such that its whole volume is inside water. What should be the minimum length of side of such a cube?
(a) 2.0m
(b) 2.5m
(c) 2.75m
(d) 3.0m

Q6. A block of ice is floating in a beaker containing liquid of specific gravity greater than one. When ice melts completely what happens to the level of liquid in the beaker?
(a) It will remain the same as before
(b) It will go down
(c) It will rise up
(d) It may or may not change depending upon size of beaker

Q7. A cylinder of mass m and radius R floats vertically in a liquid of density d. What is the height of the submerged region?

Q8. Consider the following statements:
The fraction of a ball floating inside the liquid depends upon
1. density of the liquid.
2. mass of the ball.
3. density of the ball.
Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q9. Consider the following statements:
An external pressure P0 is applied to the surface of a liquid in a container. Then,
1. the pressure on all side-wells increases by p0
2. the pressure on the bottom walls increases by p0
3. the pressure at all points inside the liquid increases by p0
Which of the statements given above is/are correct?
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 and 3 only
(d) 2 and 3 only

Q10. Let us assume that air density (0.0013g/ cm³) remains constant as we go up in the atmosphere. In such a hypothetical case, what is the approximate height of atmosphere to have 1 atmospheric pressure
(a) 4km
(b) 8km
(c) 40km
(d) 80km

S1. Ans.(d)
Sol. According to Archimedes principle,
‘A body submerging wholly or partially in a fluid is buoyed by a force equal to the weight of the displaced fluid’. When the system falls freely, effective value of g becomes zero, and so the body immersed in the vessel will become weightless. Hence, Archimedes’ principle fails.

S2. Ans.(d)
Sol. Apparent weigh = Actual weight – up thrust
If the block is floating with fully submerged in fluid, then actual weight = up thrust
∴ Apparent weight, w’ = 0

S3. Ans.(c)

S4. Ans.(b)
Sol. To use a straw to consume a soft drink is happened due to the principle of pressure.

S6. Ans.(c)
Sol. The specific gravity of liquid is greater than one and the specific gravity of water is 1 hence the level of liquid in the beaker will rise.

S8. Ans.(c)
Sol. The fraction of a ball floating inside the liquid depends only upon density of the liquid and the ball.

S9. Ans.(a)
Sol. According to Pascal’s law, the increase in pressure at any point of a fluid at rest is transmitted without loss to all other parts of the fluid.