Following Aufbau rule and Hund principle, the order of filling of the orbitals is this:

So, the first, second, and fourth option are not correct.
The third option does meet the filling order.
Answer:
Explanation:
Since scientists think planets and meteorites were made at the same time and in the same place, it seems logical that whatever a meteorite is made of is also what planets are made of.
Answer:
20 oxygen atoms
Explanation:
Li2SO4 has 4 oxygen atoms, so if there are 5 of that compound then there will be 20 oxygen atoms.
Answer:
The answer to your question is HCl + NaOH ⇒ NaCl + H₂O
Explanation:
Data
Double displacement reaction
Balanced chemical reaction
HCl + NaOH ⇒ NaCl + H₂O
Reactants Elements Products
1 Chlorine (Cl) 1
1 Sodium (Na) 1
2 Hydrogen (H) 2
1 Oxygen (0) 1
As we can see, the reaction is balanced and the coefficients of all reactants and products are 1, but the number is not written in a balanced reaction.