The freezing point of water is the same as its
a. melting point.
b. boiling point.
c. sublimation point.
d. evaporation point.

A. Melting point

Explanation

Melting point is the point of temperature at which solid changes it's state to liquid while freezing point is the point of temperature at which liquid changes it's state to solid.

Melting and freezing point of water is same i.e. 0 degree centigrade and at this temperature 80 calories of heat per gram of solid ice will convert it into liquid water.

the device is called “ rocket engine”

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 =