Answer:
18 is a
19 is c
20 i am not sure
Explanation:
18)nucleus contains protons and neutrons
Greenhouse effect is the natural phenomenon which makes the Earth's atmosphere favorable for any form of life. As the sun's rays radiates into the atmosphere, some are deflected while some are absorbed. The Earth reflects this back, causing the heat to be trapped. At night, this keeps the Earth warm enough. Without the greenhouse effect, nights would be too cold and days would be too hot that life cannot be sustained.

Aluminum ions have a charge of +3. This means that the atoms have three more protons than electrons. In order to add electrons to aluminum ions, the purification process therefore requires a large amount of electricity.
Uncharged Aluminum atom must need to lose it's electrons,in order to form the bond with oxygen which has vacant orbitals
ion
atom that has a positive or negative charge because it lost or gained one or more electrons
chemical bond
the attractive force that holds atoms or ions together
ionic bond
a chemical bond in which one atom loses an electron and the other atom gains electrons to form ions
chemical formula
a combination of chemical symbols and numbers to represent a substance
covalent bond
bond formed by the sharing of electrons between atoms
Thanks
Answer:
Acids have a high concentration of [H⁺] ions
Explanation:
In order to know about the acids, a solution is acidic when pH < 7
As pH is lower than 7, the pOH > 7
When pH = 7, solution is neutral
When pH is greater than 7, solution is basic
pH = - log [H⁺]
pOH = - log [OH⁻]
Imagine a solution of pure HCl 0.2 M
HCl → H⁺ + OH⁻
[H⁺] = 0.2 M → pH = - log 0.2 → 0.69
pH + pOH = 14
pOH = 14 - 0.69 = 13.31
10^-pOH = [OH⁻] → 10⁻¹³°³¹ = 4.89ₓ10⁻¹⁴
In conclussion [H⁺] > [OH⁻]
Flat as more oxygen and water can react over it think of it like this would a cube rust faster than a sheet