Answer:- b. +3
Explanations:- Charge of a metal ion is equal to the number of valence electrons it has as it loses these electrons to have its nearest noble gas like electron configuration.
Al has 3 valence electrons and being a metal it loses all of these and so the charge of Al ion is +3. It could be shown as:
So, the right choice is b. 3+.
The complete table is shown in figure
a) NH3 is polar as the bonds between N and H are polar. Due to asymmetry in the molecule the molecule is polar
The shape of molecule is trigonal pyramidal while its electronic geometry is tetrahedral.
b) CO2: it is a non polar molecule with polar bonds. The molecule becomes non polar as the dipole moment cancel each other. [Dipole moment is a vector quantity]
The shape is linear.
