Identical guns fire identical bullets horizontally at the same speed from the same height above level planes, one on the earth and one on the moon. which of the following three statements is/are true?
i. the horizontal distance traveled by the bullet is greater for the moon.
ii. the flight time is less for the bullet on the earth.
iii. the velocities of the bullets at impact are the same.

I. The horizontal distance traveled by the bullet is greater for the Moon.

II. The flight time is less for the bullet on the Earth.

Explanation:

Horizontal distance depends on the initial speed, height and gravity. Bullets have the same initial speed and are shot from the same height. In these conditions horizontal distance only depends on gravity, which is inversely proportional. Therefore, the less gravity the greater the horizontal distance. Gravity slows bullet and causes its impact on the ground. Since gravity is greater in Earth, the bullet hits faster on the earth.

I. The horizontal distance traveled by the bullet is greater for the Moon.

II. The flight time is less for the bullet on the Earth.

Explanation:

Bullets follow a projectile motion behavior, so they behave as uniform rectilinear motion in the horizontal axis and, they behave as free-fall motion in the vertical axis.

The bullets fall due to gravity. Since gravity is greater on Earth, bullets will fall faster, therefore flight time on Earth will be less. If flight time is less, bullets will have less time to travel horizontally before they fall so,  the horizontal distance traveled will be less on Earth.

answerscientific theory;

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 =