Which of the following factors does not affect the rate of evaporation of a liquid?
temperature
volume
wind
surface area
Correct answer is B
The rate of evaporation depends on temperature, presence of wind, the humidity of the surrounding, and the surface area of the liquid exposed to the atmosphere. It doesn't depend on the mass of the liquid. The larger the surface area, the more would be the rate of evaporation.
Formation of hydrogen bubbles at the copper plate of a primary cell is called?
polarization
back e.m.f.
electrolysis
local action.
Correct answer is A
Polarization:The hydrogen bubbles which are clinging over the surface of copper electrode anode becomes a thin film of hydrogen over the copper electrode.
This hydrogen film increases the internal resistance and reduces the emf of the cell and hence the cell soon becomes inactive. This effect is known as polarization
Which of the following quantities is not an example of force?
Mass
Tension
Weight
Friction
Correct answer is A
Mass is a measure of how much matter is in an object.
Which of the following is not correct about the molecules of a substance in a gaseous state. They?
are in a constant state of motion
have different speeds
have a temperature which is measured by the average kinetic energy
The collision between the gases is perfectly inelastic
Correct answer is D
The collision between the gases is perfectly elastic
The motion of a body is simple harmonic if the?
acceleration is always directed towards a fixed point
path of motion is a straight line
acceleration is proportional to the square of the distance from a fixed point
acceleration is constant and directed towards a fixed point
Correct answer is A
In simple harmonic motion, the acceleration of the particle is directed towards its mean position and directly proportional to its displacement