1. explain why oxygen gas must be written as o2 in a chemical equation.

Explanation:

So there are two reasons to write it as O2: 1. O2 is almost always the form of oxygen in a reaction, and 2. One needs to specify the form to describe how it will react. Other elements that usually exist as diatomic molecules are written as the dimer for the same reasons.

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spare some change and give it to the poor

explanation:

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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.