‘n’ moles of an ideal gas undergoes a process A→B as shown in the figure. The maximum temperature of the gas during the process will be:

• 
• 
• 
• 

A.

As, T will be maximum temperature where product of pV is maximum

Equation of line AB, we have

100g of water is heated from 30°C to 50°C ignoring the slight expansion of the water, the change in its internal energy is (specific heat of water is 4184 J/Kg/K)

• 8.4 kJ

• 84 kJ

• 2.1 kJ

• 4.2 kJ

A copper ball of mass 100 gm is at a temperature T. It is dropped in a copper calorimeter of mass 100 gm, filled with 170 gm of water at room temperature. Subsequently, the temperature of the system is found to be 75°C. T is given by:(Given : room temperature = 30° C, specific heat of copper = 0.1 cal/gm°C

• 1250°C

• 825°C

• 800°C

• 885° C

A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

• doubled

• four times

• one fourth

• halved

A.

doubled

A light ray is incident perpendicular to one face of a 90° prism and is totally internally reflected at the glass-air interface. If the angle of reflection is 45°, we conclude that the refractive index n

• n<2

• 
• 

• n<1/2

B.

Angle of incidence i > C for total internal reflection.
Here i = 45° inside the medium. ∴ 45° > sin−1 (1/n)
⇒ n > √2.