Which type of curved mirror uses its outside as the reflecting surface? a virtual mirror a concave mirror a plane mirror a convex mirror

a convex mirror

Explanation:

a convex mirror is a type of curved mirror that uses its outside as the reflecting surface;

A mirror whose reflecting surface curves outwards is called a convex mirror. In convex mirrors, the bulging portion is also the reflecting surface. These types of curved mirrors are widely used in vehicles as rear view mirrors since they are able to form diminished images and thus give us a larger view.

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 =