A mixture of `NO_2` and `N_2O_4` has a vapour density of 38.3 at 300K. What is the number of moles of `NO_2` in 170g of the mixture?

Answer

A-q, B-p , C-s,t , D-r

Explanation

At 75 mL of `KOH^(-)`
2.5 mmol of `KH_2PO_4` and 2.5 mmol of `K_2HPO_4` are present in a solution.So using `pH=pKa_2+ log (["salt"])/(["acid"])`
But [salt]=[acid] hence pH=`pKa_2`
At 25 ml of `KOH-`
2.5 mmol of `KH_2PO_4` and 2.5 mmol of `H_3PO_4` are present in a solution.So using `pH=pKa_1+log(["salt"])/(["acid"])`
But [salt]=[acid] hence pH=`pKa_1`
At 150 ml of `KOH-`
`K_3PO_4` salt are present in a solution due to which salt hydrolysis will take place hence,
`pH=7+1/2[p^k a_3+ log C]`
At 100 ml of KOH-
`K_2HPO_4` are present in a solution which work as amphoteric in a solution so, `pH=(P^Ka_2+P^Ka_3)/2`