I think the correct answers from the choices listed above are the first, third and the last option. Ionic compounds are compounds that dissociates into ions when in aqueous solution. From the list, NH4Cl, KF and MgO are the ionic compounds. Hope this answers the question.
The chemical formula : 3HgBr₂(Mercury(II) bromide)
<h3>Further explanation</h3>
Given
The chemical formulas of Mercury and Bromine
Required
The appropriate chemical formula
Solution
A molecular formula is a formula that shows the number of atomic elements that make up a compound.
The number of molecules is determined by the coefficient in front of the compound
the number of atoms is determined by the subscript after the atom and the coefficient
Three molecules⇒ coefficient = 3
one atom of Mercury ⇒Hg
two atoms of Bromine ⇒ Br₂
The chemical formula : 3HgBr₂
It’s either the first or second one
I think it’s the first one - the outer cells of the blastocyst