The amount of work done in blowing a soap bubble such that its diameter increases from $d$ to $D$ is ($T$ = surface tension of solution).

An azeotropic solution of two liquids has a boiling point lower than either of them when it:

$A$ bag contains $2n+1$ coins. It is known that $n$ of these coins have a head on both sides,whereas the remaining $n+1$ coins are fair. $A$ coin is picked up at random from the bag and tossed. If the probability that the toss results in a head is $\frac{31}{42}$,then $n$ is equal to

$A$ certain metal is used in the preparation of antacids. This metal accidentally catches fire and cannot be extinguished using $CO_2$. Which metal is this?

When a certain metallic surface is illuminated with monochromatic light of wavelength $\lambda$,the stopping potential for photoelectric current is $3V_0$. When the same surface is illuminated with light of wavelength $2\lambda$,the stopping potential is $V_0$. The threshold wavelength of this surface for the photoelectric effect is:

$A$ ray of light is incident on an equilateral glass prism placed on a horizontal table. For minimum deviation,which of the following is true?