A mixture `NaOH+Na_(2)CO_(3)` required 25mL of 0.1 M HCl using phenolpththalein as the indicator. However, the same amount of the mixture required 30mL of 0.1M HCl when methyl orange was used as the indicator. The molar ration of `NaOH and Na_(2)CO_(3)` in the mixture was:

Answer

5

Explanation

Let milli moles of `NaOH = x` and `Na_(2)CO_(3) = y`
`x +y = 25 xx 0.1 , x = y = 2.5` ....(1)
`x +2y = 30 xx 0.1, x +2y = 3` .......(2)
solving (1) & (2) `,x = 2, y =0.5`
`x:y = 2:0.5 =4:1, x +y = 5`