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Oxygen-18 is a naturally occuring, stable isotope and is commonly used is scientific studies as a tracer. Using the periodic table,
explain the difference between oxygen-18 and oxygen-16.
A)
Oxygen-18 contains 9 protons while oxygen-16 only contains 8 protons.
Oxygen-18 contains 10 protons while oxygen-16 only contains 8 protons,
Oxygen-18 contains 10 neutrons while oxygen-16 only contains 8
neutrons.
Oxygen-18 contains 8 electrons while oxygen-16 only contains 9
electrons.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

i would say

elctricity and magnet is conversion to it