What they have in common is that they both have the same number of atoms. Hope this helps. :)
The chemical formula of aluminium nitrate is - Al(NO₃)₃
cation is Al³⁺
anion is NO₃⁻
One Al atom binds to three nitrate groups
the options given are
2. <span>It has three aluminum (Al) atoms
this is incorrect as there's only one Al atom
3. </span><span>It has one NO3 group.
this is incorrect as there are three nitrate groups
4. </span><span>It has nine nitrogen (N) atoms
there are only 3 N atoms therefore this too is incorrect
</span>therefore the correct answer is -
It has three NO₃<span> groups
</span>
Answer : Yes, a precipitate form when a solution of calcium chloride and a solution of mercury(I) nitrate are mixed together.
The net ionic equation will be,

Explanation :
In the net ionic equations, we are not include the spectator ions in the equations.
Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.
The given balanced ionic equation will be,

The ionic equation in separated aqueous solution will be,

In this equation,
are the spectator ions.
By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.
The net ionic equation will be,
