Question

Which of the following changes is not a chemical change?

• A. Burning sodium in the atmosphere of chlorine
• B. Dropping sodium into water
• C. Cutting sodium piece with the knife
• D. Dropping sodium into a solution of sodium chloride in water​

Answer 1

The correct option is C

Cutting sodium piece with the knife

The explanation for the correct answer:

Option C: cutting sodium$\left(\mathrm{Na}\right)$ peace with the knife

• In this change, sodium is changing its shape only and no new substances are being formed here.
• Hence cutting sodium peace with a knife is not an example of chemical change

The explanations for the incorrect answers:

Option A: burning sodium in an atmosphere of Chlorine$\left(Cl\right)$

• In this change, iron sodium reacts with chlorine and produces new substance sodium chloride.
• Chemical Equation:
• $$\begin{gathered} 2\mathrm{Na}\left(\mathrm{s}\right)+{\mathrm{Cl}}_2\left(\mathrm{g}\right)\to 2\mathrm{NaCl}\left(\mathrm{s}\right) \\ \mathrm{Sodium}\mathrm{Chlorine}\mathrm{Sodium}\mathrm{chloride} \end{gathered}$$
• Hence burning sodium in the atmosphere of chlorine is an example of chemical change.

Option B: dropping sodium into water

• In this change, iron sodium reacts with water and produces a new substance sodium hydroxide.
• Chemical Equation:
• $$\begin{gathered} 2\mathrm{Na}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)\to 2\mathrm{NaOH}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right) \\ \mathrm{Sodium}\mathrm{Water}\mathrm{Sodium}\mathrm{Hydrogen} \\ \mathrm{hydroxide} \end{gathered}$$
• Hence dropping sodium into water is an example of chemical change.

Option D: dropping sodium into a solution of sodium chloride in water​

• In this change, iron sodium reacts with water and produces a new substance sodium hydroxide.
• Hence dropping sodium into a solution of sodium chloride in water is an example of chemical change.

Therefore, the right answer is option C, cutting sodium peace with a knife.