Most stable structure of Sulphur tetrachloride according to VSEPR theory is

‘S’ atom of SCl4  contains ‘4’ bond pairs and ‘1’ lone pair. All electron pairs are oriented in trigonal bipyramidal geometry.If lone pair occupies axial position it experiences three 900  repulsions whereas if it occupies equatorial position it experiences only two 90o repulsions. ∴4th structure is the most stable.