Answer: 12 Protons, 12 electrons and 16 neutrons. The number of protons and electrons always stays the same, but the neutrons is the mass-protons. In this case, 28-12=16 neutrons.
Dry, white powder, soluble in water to form a slightly basic solution
Answer is: another name for groups of elements is family.
There are 18 numbered groups in the periodic table.
The elements in a group have similar physical or chemical characteristics and some groups have a specific name, for example group 17 (the halogens).
Elements in the group have the same number of valence electrons, for example, chemical elements in group 15 of the periodic table have neutral atom with a valence electron configuration of ns²np³.
In order to answer this, we mus know the data for the heat of combustion of propane. This is an empirical data that you can search online. The heat of combustion is -2220 kJ/mol. The molar mass of propane of 44.1 g/mol. The solution is as follows:
ΔH = -2220 kJ/mol (1 mol/44.1 g)(1000g/1kg)(20 kg)
<em>ΔH = -1006802.721 kJ or -1 GJ</em>