1. I am getting answer for this question 6.51 mPa which is not in options.
2. In another PDF for same question they brought answer 46mPa but in their solution they have used lewis equation which is objectionable. (Refer 2nd attached image)
3.velocity factor given in question is 1.5 but in any case it can not exceed 1 because if we observe its formulas then we can say this. (I have attached image for formulas of vel factor from design khurmi)
I dont know how to deal with all these, I have already spent lot of time on this problem someone please help…..
Option B is the correct answer. The second image posted contains your solution. For a detailed explanation of Lewis equation and velocity factor, refer the barth velocity factor page in the following url: