Each orbit surrounding an atom is allowed A LIMITED NUMBER OF ELECTRONS.
The number of orbit that an atom has is determined by its atomic number, the higher the atomic number the higher the number of orbit in the atom and each orbit has different energy level. Each orbit can only take fixed number of electron. The first shell can only take two electrons while the subsequent shells can only take eight electrons. When an orbit has taken the highest number of electron possible, the remaining electrons are moved to the next shell.
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the answer is Yes, a hydrocarbon is any compound that contains hydrogen and oxygen.
The reaction equation is:
2HF(aq) + Ba(OH)₂(aq) → BaF₂(s) + H₂O (aq)
Writing the ionic form of this equation:
2H⁺ + 2F⁻ + Ba⁺² + 2OH⁻ → BaF₂ + H⁺ + OH⁻
The solubility of barium fluoride is 0.16 grams per 100 ml of water, which means that it is an insoluble compound. Moreover, spectator ions are those that remain unchanged before and after a reaction, so they "spectate" the reaction. In this case, the ions unchanged before and after the reaction are H⁺ and OH⁻.
The heat is involved in the production of 5.0 mol of MgO is 180 Kj
calculation
2 Mg (s) +O2 → 2 MgO
From the equation above two moles of MgO is used therefore
72.3 is for 2 moles
that is 72.3 kj = 2moles
? = 5 moles
by cross multiplication
= 72.3 kj × 5/2 = 180 Kj

Rusting of iron is the most familiar example of corrosion. It is a process in which an iron reacts with atmospheric oxygen and moisture to form a reddish brown substance iron oxide, which is commonly known as rust.


