Question

Which of the following molecules have zero dipole moment and tetrahedral structure?
(A) $CC{l_4}$
(B) $SnC{l_2}$
(C) $SnC{l_4}$
(D) $C{O_2}$

Answer 1

Hint : Dipole moment arises when there is a separation of charge. It occurs due to the difference in electronegativity between the atoms that are chemically bonded. Dipole moment is larger, if the difference in electronegativity is larger.

Complete Step By Step Answer:
In $CC{l_4}$ molecule, tetrahedral symmetry exists. So, the dipole moment of the three $C - Cl$ bonds present on one side will give a resultant moment which is equal and opposite to the dipole moment of the single $C - Cl$ bond present on the opposite side. Therefore, the resultant dipole moment will be zero.
The electronic configuration of $Sn$ is $[kr]4{d^{10}}5{s^2}5{p^2}$ . There will be a lone pair of electrons on $Sn$ and the two electrons present in $5p$ will be used by the two chlorine atoms in bonding. The resulting geometry will be trigonal pyramidal and the dipole moment will not be equal to zero.
The molecule $SnC{l_4}$ is a symmetric compound. The dipole moment will be zero because the dipole moments in opposite directions cancel each other. $SnC{l_4}$ has a tetrahedral geometry with tin at the center, one chlorine extending straight up above tin and three other chlorine atoms extending outside and down from the tin.
$C{O_2}$ has linear molecular geometry and symmetric distribution of electrons. In $C{O_2}$ , each $C - O$ bond is polar and the two $C - O$ bond dipoles are equal in magnitude and cancel each other as they are oriented at ${180^ \circ }$ to each other. So, there will be no net dipole moment in carbon dioxide molecules.
Therefore, option A and C are the correct answers.

Note :
Carbon tetrachloride and tin tetrachloride have tetrahedral structure and zero dipole moment because all the bond dipoles cancel each other which gives net dipole moment zero. Carbon dioxide has zero dipole moment but the structure is not tetrahedral.