Hello, Bhupendra. I suppose you have already performed reliability analyses. If not, I suggest performing them. I generally use SPSS and performa a Cronbach Alfa Test. SPSS allows you to establish the increases in the instrument's reliability when you elminate or drop one item.
In addition, I suggest you this article that deals with discrimination power. Hope this helps. http://www.uv.es/revispsi/articulos1.12/6FERRANDO.pdf
Let me know how it goes.
Hernan A. Vera, Pontifical Catholic University of Puerto Rico.