Question

Assertion : Smaller drops of liquid resist deforming forces better than the larger drops.
Reason : Excess pressure inside a drop is directly proportional to its surface area.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

Also excess pressure inside a bubble is

$P=\frac{4T}{R}$
where $R$ is radius of bubble.
Since excess pressure is inversely proportional to radius, hence excess pressure inside a smaller drop is large as compared to larger drop due to which smaller drop resists deforming forces better than a larger drop
Also
$P=\frac{4T}{R}$
$P\propto \frac{1}{\Delta A}$
Also $P=\frac{4T}{R}=\frac{4W}{R\cdot \Delta A}$
$\left(\because T=\frac{W}{\Delta A}\right)$
$\Rightarrow P\propto \frac{1}{\Delta A}$
Hence, excess pressure is inversely proportional to surface area.