For every 100 joules of useful energy output , the heater wastes 100 joules , find the input energy of the heater.

you have to draw the persons position over there

d) physical means can be used to separate the components of air.

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 =