Question

Assertion :$CaC{O}_3\left(s\right)+2HCl\left(aq\right)⟶CaC{l}_2\left(aq\right)+H_{2}C{O}_3\left(aq\right)$
$CaC{O}_3\left(s\right)+2H^{+}\left(aq\right)+2C{l}^{-}\left(aq\right)⟶\left[C{a}^{2+}\right(aq)+2C{l}^{-}(aq\left)\right]+H_{2}C{O}_3\left(aq\right)$
Thus, net reaction is
$CaC{O}_3\left(s\right)+2H^{+}\left(aq\right)⟶C{a}^{2+}\left(aq\right)+H_{2}C{O}_3\left(aq\right)$
This is an exothermic reaction (in which heat is evolved) and thus there is thermal decomposition of carbonic acid into gaseous carbon dioxide and water. Reason: Heat evolved in the reaction (exothermic) causes decomposition of $H_{2}C{O}_3\left(aq\right)$ into $C{O}_2\left(g\right)$ and $H_{2}O\left(l\right)$ $H_{2}C{O}_3⟶H_{2}O\left(l\right)+C{O}_2\left(g\right)$Thus, $H_{2}C{O}_3$ is unstable.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

As we know,

$HCl$ and $CaC{l}_2$ exists as ions in solution so net reaction will be

$CaC{O}_3\left(s\right)+2H^{+}\left(aq\right)+2C{l}^{-}\left(aq\right)⟶\left[C{a}^{2+}\right(aq)+2C{l}^{-}(aq\left)\right]+H_{2}C{O}_3\left(aq\right)$
Thus, net reaction is
$CaC{O}_3\left(s\right)+2H^{+}\left(aq\right)⟶C{a}^{2+}\left(aq\right)+H_{2}C{O}_3\left(aq\right)+\Delta H$

Also as it is exothermic reaction so heat evolved will be causes decomposition of