Answer: Option (a) is the correct answer.
Explanation:
Strontium chloride (\(SrCl_{2}\)) is an ionic compound. And, as it is ionic in nature so there will be strong force of attraction between the two oppositely charged ions that is, \(Sr^{2+}\) and \(Cl^{-}\).
At room temperature, \(SrCl_{2}\) exists in solid state.
Whereas ethane (\(C_{2}H_{6}\)) at room temperature exists as a gas.
Chemical formula of water is \(H_{2}O\) and at room temperature it exists in liquid state.
\(Cl_{2}\) is a dichlorine molecule and it exists as a gas at room temperature.
Thus, we can conclude that out of the given options \(SrCl_{2}\) would you expect to be the hardest at room temperature.
