Question

The compounds having coordinated water are:
I. CrCl$_3$.6H$_2$O
II. BaCl$_2$.2H$_2$O
III. CuSO$_4$.5H$_2$O

• A. II, III only
• B. I, III only
• C. I, II only
• D. I, II, III

Hint:

Transition metal hydrates often involve coordinated water due to the ability of transition metals to form coordination complexes. Hydrates of s-block and p-block elements are more likely to have lattice water.

Answer 1

The Correct Option is B

Step 1: Understand coordinated water.
Coordinated water refers to water molecules that are directly bonded to the central metal ion in a coordination complex. These water molecules are part of the coordination sphere.
Step 2: Analyze each compound. \begin{itemize} \item I. CrCl$_3$.6H$_2$O: This compound exists as a hydrate where some or all of the water molecules are coordinated to the chromium(III) ion. The formula can be written as [Cr(H$_2$O)$_6$]Cl$_3$ or isomers with some Cl$^-$ ions inside the coordination sphere. In either case, some water molecules are coordinated. \item II. BaCl$_2$.2H$_2$O: Barium is an s-block element and typically forms ionic hydrates where water molecules are held by electrostatic forces in the crystal lattice but are not directly coordinated to the metal ion in a complex. \item III. CuSO$_4$.5H$_2$O: Copper(II) sulfate pentahydrate has the structure [Cu(H$_2$O)$_4$]SO$_4$.H$_2$O. Four water molecules are coordinated to the copper(II) ion, forming a complex ion, while one water molecule is a lattice water. Thus, it has coordinated water. \end{itemize}
Step 3: Identify the compounds with coordinated water.
Compounds I and III have coordinated water molecules. Final Answer: \[ \boxed{\text{I, III only}} \]