Answer:

The air in the atmosphere consists of nitrogen, oxygen, which is the life-sustaining substance for animals and humans, carbon dioxide, water vapour and small amounts of other elements (argon, neon, etc.). Higher in the atmosphere air also contains ozone, helium and hydrogen.
Answer:


Explanation:
Given



Required
Determine the area
The area of a triangle is :

By substituting values for the x and y coordinates of A, B and C;
We have:

So:
For instance



The area is:






Answer:
Physical change
Explanation:
Physical change -
It is the type of reversible change , where there is change in the state of the matter , is referred to as a physical change .
There is no chemical process involved during state change , i.e. , no new substance is formed .
Hence , from the given statement of the question, the correct term is physical change.
<h3>Answer:</h3>
Number of Protons = 9
Number of Neutrons = 9
Number of Electrons = 10
<h3>Explanation:</h3>
Number of Protons:
The number of protons present in any atom are equal to the atomic number of that particular atom. Hence, as the atomic number of Fluorine is 9 therefore, it contains 9 protons.
Number Neutrons:
The number of neutrons present in atom are calculated as,
# of Neutrons = Atomic Mass - # of protons
As given,
Atomic Mass = 18
# of Protons = 9
So,
# of Neutrons = 18 - 9
# of Neutrons = 9
Number of Electrons:
As we know for a neutral atom the number of electrons are exactly equal to the number of protons present in its nucleus. So, for 9 protons in neutral Fluorine atom there must be 9 electrons. But, we are given with Fluoride Ion (i.e. F⁻) so it contains one extra electron hence, it contains the total of 10 electrons respectively.