C) alternately increase and decrease
C. Usually when an atom loses or gains an electron, it is because it is trying to satisfy the Octet Rule. The Octet Rule states that an atom is at its stablest when it has 8 valence electrons (two in helium's case)
If you look on the periodic table, elements on the left (Alkaline Metals) are the most reactive because they only have one valence electron (or electron in the outer shell). Elements on the right (Noble Gases) are the least reactive because they have a full outer shell of 8 valence electrons.
Later on you will find that as stability decreases as you go down the periodic table but that is a discussion for a different time.
Answer:
See the explanation below.
Explanation:
a)
Pumping water requires equipment with closed housing, so that water is not irrigated from the pumping point.
Fans in some applications do not require closed housings, as air irritation does not create anomalies or areas of nonconformity at the air pumping point.
b)
The pressures in water pumping equipment are usually much higher than those generated with air equipment, since the density of water is much higher than that of air, almost 1000 times higher.
