On which factor does quantity of heat depend and what effect on the molecules of matter when the temperature is varied ?

I don’t know the answer for the first one

but for the second one ‘what effect on the molecules of matter when the temperature is varied?’

When the temperature is varied — the kinetic particle theory states that matter is made up of particles that are constantly moving or in a continual state of motion.

When temperature is increased, the molecules gain more energy (via heat) so they move faster and have more frequent collisions with one another.

When temperature is decreased, the molecules lose kinetic energy, so they move slower and have less frequent collisions.

the average speed is 24.57 km/hr

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =