Question

What is the molecular geometry of $ AsC{{l}_{3}} $ ?
(A) Tetrahedral.
(B) Trigonal Pyramidal.
(C) Trigonal Planar.
(D) T-Shaped.

Answer 1

Hint: We know that the molecular geometry of a molecule gives the general shape, bend angles, Torsional angles, bond lengths etc. the Propertius like polarity, reactivity, Colour, state of matter etc. can be determined by knouting the molecular geometry of the molecule.

Complete step by step solution:
Here we have a basic ideology that molecular geometry is determined with the help of some special techniques named as spectroscopic and diffraction methods, example: X Rays , NMR, $ 1R, $ Raman spectroscopy etc. The geometry of individual molecules is discussed below;
To determine the molecular geometry of arsenic trichloride, $ AsC{{l}_{3}} $ , we must take a look at its Lewis structure. One arsenic trichloride molecule will have a total of $ 26 $ valence electrons $ -~5~ $ from the arsenic atom and $ 7 $ from each of the three chlorine atoms.
The arsenic atom will be bonded to the three chlorine atoms through single bonds that account for 6 of the $ 24 $ valence electrons. Each of the chlorine atoms will have three lone pairs, which will bring the number of valence electrons used to $ 24. $
The remaining two valence electrons will be placed on the arsenic atom as a lone pair.

According to Theory, the geometry of $ AsC{{l}_{3}} $ is trigonal planar.
The correct answer is option (C).

Note :
Remember that $ VSEPR $ is a short form of the valence shell electron pair repulsion theory. This theory. Can predict the geometry of many molecules, especially those belonging to the p block, in theory, the geometry of a molecule atom. The geometry of a molecule depends upon the number of valence shell electrons around the central atom. The pairs of electrons try to occupy minimum repulsion and maximal distance orientation in space.