Class 12th

Given below are two statements :                                                       

Statement I : Emulsions of oil in water are unstable and sometimes they separate into two layers on standing.

Statement II : For stabilization of an emulsion, excess of electrolyte is added. In the light of the above statements, choose the most appropriate answer from the options given below :

Statement – I : The reactance of an ac circuit is zero. It is possible that the circuit contains a capacitor and an inductor.

Statement – II : In ac circuit, the average power delivered by the source never becomes zero.

In the light of the above statements, choose the correct answer from the options given below

A proton, a deuteron and an α - particle with same kinetic energy enter into a uniform magnetic field at right angle to magnetic field. The ratio of the radii of their respective circular paths is

The soft-iron is a suitable material for making an electromagnet. This is because soft iron has

What will be the most suitable combination of three resistors A = $2\Omega$ , B = $4\Omega$ , C = $6\Omega$ so that $\left(\frac{22}{3}\right)\Omega$ is equivalent resistance of combination

let f(x) be a quadratic polynomial such that f(-2) + f(3) = 0. If one of the roots of f(x) = 0 is -1, then the sum of the roots of f(x) = 0 is equal to:

In a potentiometer arrangement, a cell gives a balancing point at 75 cm length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emef's of two cells respectively is 3:2, the difference in the balancing length of the potentiometer wire in above two cases will be __________ cm.

Let R₁ = $\left\{\left(a,b\right)\in N*N:\left|a-b\right|\le 13\right\}and$  

R₂ =   $\left\{\left(a,b\right)\in N*N:\left|a-b\right|\ne 13\right\}.$ Then on N :

Two identical charged particles each having a mass 10g and charge 2.0 * 10^-7 C are placed on a horizontal table with a separation of L between them such that they stay in limited equilibrium. If the coefficient of friction between each particle and the table is 0.25, find the value of L. [Use g = 10ms^-2]

When light of frequency twice the threshold frequency is incident on the metal plate, the maximum velocity of emitted electron is ${\upsilon }_1.$ When the frequency of incident radiation is increased to five times the threshold value, the maximum velocity of emitted electron becomes ${\upsilon }_2.$ If ${\upsilon }_2=x{\upsilon }_1,$ the value of x will be __________.