Answer:
1. hydrogen - H
2. helium - He
3. sodium - Na
4. magnesium - Mg
5. potassium - K
Explanation:
Hydrogen is the element of group 1 and first period. The atomic number of hydrogen is 1 and the symbol of the element is H.
The electronic configuration of the element hydrogen is:-

Helium is the element of group 18 and first period. The atomic number of helium is 2 and the symbol of the element is He.
The electronic configuration of the element helium is:-

Sodium is the element of group 1 and third period. The atomic number of sodium is 11 and the symbol of the element is Na.
The electronic configuration of the element sodium is:-

Magnesium is the element of group 2 and third period. The atomic number of magnesium is 12 and the symbol of the element is Mg.
The electronic configuration of the element magnesium is:-

Potassium is the element of group 1 and forth period. The atomic number of potassium is 19 and the symbol of the element is K.
The electronic configuration of the element potassium is:-

The electrons in bonds (bonding domains) differ from lone
pairs (non-bonding domains) is because the bonding
domains are bonded to the central atom vs the lone pairs are just stuck on as
extra electrons. The difference of bonding domains from non-bonding
domains is that the bonding domains are bonded to the central atom and the
non-bonding domains are just stuck on as extra electrons.
yeag
Explanation:
2SrO + 4NO2 + O. The thermal decomposition of strontium nitrate to produce strontium oxide, nitrogen dioxide and oxygen. This reaction takes place at a temperature of over 570°C
The Correct Answer is Eletric Current I think