Question

As the density of liquid increases, the buoyant force exerted by it
A. Increases
B. Decreases
C. Will remain constant
D. All may be correct

Answer 1

Hint: The buoyant force exerted by a liquid depends on the density of liquid, volume of the object immersed and the acceleration due to gravity. We can arrive at the answer easily by comparing the given quantity with the equation of buoyant force.

Complete step by step solution:
According to Archimedes principle, the magnitude of buoyant force experienced by an object in the liquid is equal to the weight of the liquid displaced by the object placed in the liquid
If V_immersed is the volume immersed by the object in the liquid, ρ is the density of the liquid, g is the acceleration due to gravity then buoyant force exerted by the liquid on the object is equal to FB.
FB = ρ V_immersed g
In the above equation we can see that the buoyant force is proportional to the density of the liquid. From this we can conclude that, if the volume immersed by the object in the liquid remains same, then, as the density of the liquid increases the buoyant force exerted by the liquid increases.

Thus, the correct choice is option A.

Note: Consider an object placed in liquid A. Say, it floats in liquid A in such a way that the three fourth of the volume of the object is immersed in liquid A. If the same object is placed in liquid B, one half of the volume of the object is immersed in liquid B. Here the density of liquid B is greater than liquid A. In both the cases, the weight of the object is balanced by buoyant force on the object. As weight of the object is not changed, the buoyant force exerted on the object in both the cases has to remain the same. Here the product of volume immersed and density is the same in both the cases. Here, we can conclude that if the volume immersed is different then as the density of the liquid increases buoyant force may not increase.