Decide which element probably forms a compound with hydrogen that has a chemical formula most and least similar to the chemical formula of the compound formed by hydrogen and oxygen.

The question is incomplete, the complete question is shown in the image attached to this answer

Most similar - sulphur

least similar- gallium

Explanation:

The compound formed when hydrogen reacts with oxygen is water. The chemical formula of water is H2O.

Water is very similar to H2S which is the compound formed when hydrogen reacts with sulphur. The bonds in water and H2S are both polar covalent bonds.

However, gallium is a metal and its hydride (GaH3) is least similar to water.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements