<p>A solution contains&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>N</mi><msub><mi>a</mi><mn>2</mn></msub><mi>C</mi><msub><mi>O</mi><mn>3</mn></msub><mo>&#160;</mo><mi>a</mi><mi>n</mi><mi>d</mi><mo>&#160;</mo><mi>N</mi><mi>a</mi><mi>H</mi><mi>C</mi><msub><mi>O</mi><mn>3</mn></msub></math>. 10 mL of the solution required 2.5 mL of 0.1 M&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>H</mi><mn>2</mn></msub><mi>S</mi><msub><mi>O</mi><mn>4</mn></msub></math>&nbsp;for neutralisation using phenolphthalen as indicator. Methyl orange is then added when a further 2.5 mL of 0.2 M&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>H</mi><mn>2</mn></msub><mi>S</mi><msub><mi>O</mi><mn>4</mn></msub></math>&nbsp;was required. The amount of&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>N</mi><msub><mi>a</mi><mn>2</mn></msub><mi>C</mi><msub><mi>O</mi><mn>3</mn></msub></math>&nbsp;and&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>N</mi><mi>a</mi><mi>H</mi><mi>C</mi><msub><mi>O</mi><mn>3</mn></msub></math>&nbsp;in 1 litre of the solution is:</p>