Question

A gas ‘X’ that, turns limewater milky, is evolved when a piece of ___________ reacts with aqueous HCl.​

• A. Gold
• B. Iron
• C. Chalk
• D. Magnesium ribbon

Answer 1

The correct option is C Chalk

• The gas X which turns the lime water milky is definitely $C{O}_2$.
• We have discussed that when metal carbonate reacts with $HCl$ , $C{O}_2$ gas is evolved.
• Thus the reaction is: $Metalcarbonate\left(s\right)+HCl\left(g\right)\to Metalsalt\left(aq\right)+H_{2}O\left(l\right)+C{O}_2\left(g\right)$
• In the given options only Chalk is a metal carbonate which is calcium carbonate.
• Thus, the correct answer is C.