11.

The speed of sound is maximum in

• water
  
  

• vacuum
  
  

• air
  
  

• steel

When a glass rod is rubbed with silk, then which type of charge is created on it?

• Positive charge
  
  

• Negative charge
  
  

• Electric charge
  
  

• None of these

On a moving plane mirror, incident ray forms an angle of 60°, then what will be the reflected angle?

• 60°
  
  

• 90°
  
  

• 30°
  
  

• 120°

Which one of the following is a renewable resource of energy?

• Petroleum
  
  

• Groundwater
  
  

• Natural gas
  
  

• Coal

Which physical unit is obtained by the ratio of momentum and velocity of matter?

• Acceleration
  
  

• Mass
  
  

• Velocity
  
  

• Force

Brine' is

• Common name of bleaching powder
  
  

• aqueous solution of chlorine
  
  

• saturated solution of NaCl
  
  

• aqueous solution of Na₂SO₄

Momentum of a particle of mass m is p. Its Kinetic Energy will be

• $p^{2}m$

• $\frac{p^2}{m}$

• $mp$

• $\frac{p^2}{2m}$

Who discovered X-rays?

• Roentgen
  
  

• Maxwell
  
  

• Rutherford 
  
  

• Torricelli

A battery of 15 V is connected to a parallel group of resistance of 4, 10 and 20 $\mathrm{\Omega }$. The current in the circuit will be

• 6 A
  
  

• 4 A
  
  

• 8 A
  
  

• 2 A

One nanometer is equal to

• 10^-7cm

• 10^-8cm

• 10^-6m

• 10^-9m