# NEET Chemistry Redox Reactions Questions Solved

A mixed solution of potassium hydroxide and sodium carbonate required 15 mL. of an N/20 HCI solution when titrated with phenolphthalein as an indicator. But the same amount of the solution when titrated with methyl orange as an indicator required 25 mL of the same acid. The amount of KOH present in the solution is

(1) 0.014g

(2) 0.14g

(3) 0.028g

(4) 1.4 g

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(1) KOH + Na2aO3

a M.e.b.M.e.

a + $\frac{\text{b}}{\text{2}}$ = 15 × $\frac{1}{20}$

2a + b= 1.5 … (i) (in presence of phenolphthalein)

a + b = 25 × $\frac{1}{20}$= 1.25… (ii) (in presence of Methyl orange)

by solving (i) & (ii) a = 0.25 m.e

mass of KOH = $\frac{0.25}{1000}×$ 56 = 0. 014 gm

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