Question

which of the following equations shows a physical change? (1 point)
\\(\ce{h_{2}o(s) \
ightarrow h_{2}o(l)}\\)
\\(\ce{n_{2}o_{5} \
ightarrow no_{2} + o_{2}}\\)
\\(\ce{caco_{3} \
ightarrow cao + co_{2}}\\)
\\(\ce{c_{12}h_{22}o_{11} + 12o_{2} \
ightarrow 12co_{2} + 11h_{2}o}\\)

Explanation:

A physical change involves a change in state or appearance without forming new substances. The reaction $\ce{H2O(s) -> H2O(l)}$ is the melting of ice (solid water) to liquid water, where the substance remains $\ce{H2O}$ (no new substance is formed). The other reactions produce new substances (e.g., $\ce{NO2}$ and $\ce{O2}$ from $\ce{N2O5}$), indicating chemical changes.

Answer:

A. $\ce{H2O(s) -> H2O(l)}$