Answer: a)
Explanation:
The buoyant force, as stated by Archimedes’ principle, is equal to the weight of the liquid that occupies the same volumen as the submerged object, as follows:
Fb = δ.V.g
If this force is larger than the weight of the object (that means that the fluid is denser than the solid), the object floats, which is the case for silver and mercury.
Instead, silver density is larger than water density, which explains why the pure silver ingot sinks.
Finally, as mercury is denser than water, we conclude that for a same object, the buoyant force in mercury is larger than in water (exactly 13.6 times greater).
Slope of a curve Y plotted against X is mathematically given as

now here we can see that if similarly graph is plotted against distance and time then slope is given as

here we can say that above is ratio of small distance and very small interval of time.
so here we can say that this ratio of distance and time for very small interval of time is known as instantaneous speed of the object which is falling freely under gravity.
So here slope of the graph will represent the speed at a given instant.
Answer:
Melting and frezzing are physical changes
Answer:
Explanation:
θ( p ) + θ( r ) = 90
θ (r) = angle of refraction and θ ( p ) is polarising angle.
given θ ( r ) = 31.8
θ ( p ) = 90 - 31.8 = 58.2 degree
ii ) Tanθ ( p ) = n ( refractive index ) = Tan 58.2 = 1.6