As water is boiled, kinetic energy causes<span> the </span>hydrogen bonds to break<span> completely and allows water molecules to escape into the air as gas (steam or water vapor). When water freezes, water molecules form a crystalline structure maintained by </span>hydrogen bonding<span>. Solid water, or </span>ice<span>, is less dense than liquid water.</span>
In all atoms, the number of protons and the number of electrons is always the same. The number of neutrons is very roughly the same as the number of protons, but sometimes it's rather more. The number of protons in an atom is called the atomic number and it tells you what type of atom you have.
The sum of angels of a quadrilateral is equal to 360°.
∠A = 360 - (60 + 45 + 100) = 155
