A student carries out a titration using $20.0\,\text{cm}^3$ of $0.0250\,\text{mol dm}^{-3}$ aqueous sodium carbonate and dilute hydrochloric acid. Exactly $15.5\,\text{cm}^3$ of the dilute hydrochloric acid is required to react completely with the aqueous sodium carbonate. Calculate the concentration, in $\text{mol dm}^{-3}$, of the dilute hydrochloric acid.
State the colour shown by methyl orange in alkaline solution.
Write the formula for the ion present in aqueous solutions of alkalis.
Calculate the volume, at r.t.p., of carbon dioxide formed, in $\text{cm}^3$, when $2.65\,\text{g}$ of sodium carbonate is allowed to react with excess hydrochloric acid.
Define what is meant by strong in the phrase strong acid.
State one further adverse effect of oxides of nitrogen.
Oxides of nitrogen are removed from car exhausts by catalytic converters. Complete the symbol equation for the reaction taking place in catalytic converters.\n\n$2\text{CO} + 2\text{NO} \rightarrow \ldots + \ldots$