The half life of radioactive elements is 600 yr the fraction of sample that would remain after 3000 yr is

 

1.  1/2

 

2.  1/16

 

3.  1/8

 

4.  1/32

A particle moves along with x-axis. The position x os particles with respect to time t from origin given by x = b₀ + b₁t + b₂t². The acceletration of particle is

 

1.  b₀

Root mean square speed of the molecules of ideal gas is v. If pressure is increased two times at constant temperature, then the rms speed will become

 

1.  

1 mol of gas occupies a volume of 200 mL at 100 mm pressure. What is the volume occupied by two moles of gas at 400 mm pressure and at same temperature?

 

1.  50 mL

A charged particle travels along a straight line with a speed v in a region where both electric foeld E and magnetic field B are present. If follows that

 

1.  |E| = v |B| and two fields are parallel

What will be the wave velocity, if the radar gives 54 waves/min and wavelength of the given wave is 10 m?

 

1.  4 m/s

A transformer of 100% efficiency has 200 turns in the primary coil and 40000 turns in secondary coil. It is connected to a 220 V main supply and secondary feeds to a 100 kΩ resistance. The potential difference per turn is

 

1.  1.1 V

 

2.  25 V

 

3.  18 V

 

4.  11 V

A thin convex lens of refractive index 1.5 has 20 cm focal length in air. If the lens is completely immersed in a liquid of refractive index 1.6, its focal length will be

 

1.  -160 cm

 

2.  - 100 cm

 

3.  + 10 cm

 

4.  +100 cm

SI unit of permittivity is