Question

Assertion: A molecule of silicon tetrachloride $ \left( {SiC{l_4}} \right) $ is nonpolar.
Reason: The four bonds in $ SiC{l_4} $ are identical and the molecule has a tetrahedral structure.
(A) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion
(B) Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion
(C) Assertion is correct but Reason is not correct
(D) Assertion is not correct but Reason is correct
(E) Both the Assertion and Reason are not correct

Answer 1

Hint: A nonpolar substance has no separation of charge, so no negative or positive poles are formed. The electrical charges of non-polar molecules are evenly distributed across the molecule so there is no polarity. This occurs if the molecule has no lone pair.

Complete Step by step Solution:
Silicon tetrachloride is a colorless, fuming liquid with a pungent odor. It is prepared by chlorination of various silicon compounds such as ferrosilicon, silicon carbide.
Silicon tetrachloride’s crystalline structure is tetrahedral and even the coordination geometry of the compound is tetrahedral.
In tetrahedral molecular geometry, a central atom is located at the center with four other particles at corners of a tetrahedron. The bond angle between the two bonds of the tetrahedral is degree.
As the geometry of silicon tetrachloride is tetrahedral, it has Si as the central element and has coordination number as four. The bond length is of equal length and at an equal angle. When chlorine forms a compound with silicon, it forms it in such a way that they have maximum distance between them and minimum repulsion. This results in no net dipole moment.
Therefore, the correct answer is option A as the assertion and reason both are correct and the reason is the correct explanation of assertion.

Note:
Silicon tetrachloride is used in smoke screens and to make various silicon related materials and chemicals. Silicon tetrachloride is corrosive to metals and tissue in presence of moisture. The molecules are attracted only by Vander Waal forces and thus are liquid in nature.