Two moles of exygen is mixed with eight moles of helium. The effective specific heat of the mixture at constant volume is

• 1.3 R

• 1.4 R

• 1.7 R

• 1.9 R

On heating, the temperature at which water has minimum volume is

• 0° C

• 4° C

• 4 K

• 100° C

In damped oscillations, the amplitude of oscillations is reduced to one-third of its initial value a₀ at the end of 100 oscillations. When the oscillator completes 200 oscillations, its amplitude must be

• $\frac{{\mathrm{a}}_0}{2}$

• $\frac{{\mathrm{a}}_0}{6}$

• $\frac{{\mathrm{a}}_0}{9}$

• $\frac{{\mathrm{a}}_0}{4}$

A particle executes simple harmonic motion with a time period of 16 s. At time t = 2 s, the particle crosses the mean position while at t = 4s, its velocity is 4 ms^-1. The amplitude of motion in metre is

• $\sqrt{2} \mathrm{\pi }$

• $16\sqrt{2} \mathrm{\pi }$

• $\frac{32\sqrt{2}}{\mathrm{\pi }}$

• $\frac{4}{\mathrm{\pi }}$

For a simple pendulum, the graph between T² L and is

• a straight line passing through the origin

• parabola

• circle 

• ellipse

Charges + 2q, + q and + q are placed at the comers A, B and C of an equilateral triangle ABC. If E is the electric field at the circumcentre 0 of the triangle, due to the charge + q, then the magnitude and direction of the resultant electric field at O is

• E along AO

• 2E along AO

• E along BO

• E along CO

N identical drops of mercury are charged sumultaneously to 10 V. When combined to form one large drop, the potential is found to be 40 V, the value of N is

• 4

• 6

• 8

• 10

The electrostatic potential energy between proton and electron separated by a distance 1 $\stackrel{\circ }{\mathrm{A}}$ is

• 13.6 V

• 27.2 eV

• 14.4 eV

• 1.44 eV

The plates of a parallel plate capacitor with air as medium are separated by a distance of 8 mm. A medium of dielectric constant 2 and thickness 4 mm having the same area is introduced between the plates. For the capacitance to remain the same, the distance between the plates is

• 8 mm

• 6 mm

• 10 mm

• 12 mm

40.

The resistance of a wire at room temperature 30˜C is found to be 10 Ω. Now to increase the resistance by 10%, the temperature of the wire must be [The  temperature coefficient of resistance of the material of the wire is 0.002/°C]

• 36°C

• 83°C

• 63°C

• 33°C