1) A mass of 20kg was lifted from a height of 5m to 12m. How much work was done?

1400joules

Explanation:

work(j)= force × distance.

Distance is from 5m to 12 that is 7m

Force, we weren't given, and the formula is mass × acceleration due to gravity. mass is 20kg and a is 10 or 9.8

f= 20×10

f=200

work= 200 × 7

work= 1400joules

Hope it helped(...and is correct )

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 =