1. In re-crystallization method, if a compound was crystallized during the hot filtration step, what is the best way to overcome this problem? 2. In coupling reaction for the preparation of Methyl orange indicator, NaCl was added in re-crystallization step, give reason and discuss.

3. How poly phenols (tannins) can be removed from a solution containing Caffiene?

4. Which method is more efficient for the extraction of natural products? Reflux or Soxhlet? Why?

5. How a mixture of salicylic acid and 3-methylxanthine can be separated?

im pretty sure its b

the answer is d. 74.02

i think it's letter a.

answer : (a) volume of the gas = 8.67 ×   l

                (b) second virial coefficient b = -1.21226 l/mole

solution :   given,     t = 300k

                                p = 20atm

                                z = 0.86

                                n = 8.2 mmoles = 8.2 × moles

                                r =   0.082 l atm/k/mol

        find,     (a) volume of gas   and (b) second virial coefficient b at 300k.

formula used :            

                          and            

(a)            

                    = \times 0.082\times 300}{20}[/tex]

                    = 8.67 ×   l

(b)      

                    = (0.00867-1) × 8.659

                    = - 8.5839 l/mole