Answer:

is time required to heat to boiling point form initial temperature.
Explanation:
Given:
initial temperature of water, 
time taken to vapourize half a liter of water, 
desity of water, 
So, the givne mass of water, 
enthalpy of vaporization of water, 
specific heat of water, 
Amount of heat required to raise the temperature of given water mass to 100°C:



Now the amount of heat required to vaporize 0.5 kg of water:

where:
mass of water vaporized due to boiling


Now the power rating of the boiler:



Now the time required to heat to boiling point form initial temperature:


I think the answer is A.........
Answer:
Time, 
Explanation:
Given that,
When a high-energy proton or pion traveling near the speed of light collides with a nucleus, it may travel
before interacting.
Let t is the time interval required for the strong interaction to occur. It will move with the speed of light. So,

So, the time interval is 
Answer:
D.
Explanation:
Force is strength and energy as an attribute of physical action or movement.
Answer = 330 m/s
The wave equation is as follows:
Wave speed = wavelength x frequency
The known values are:
Wavelength = 3m
Frequency = 110 Hz
Substitute the known values into the wave equation to find the wave speed.
Wave speed = 3 x 110
Wave speed = 330 m/s