Question

Match List I with List II:

• A. A – IV; B – I; C – II; D – III
• B. A – IV; B – III; C – II; D – I
• C. A – IV; B – III; C – V; D – I
• D. A – II; B – III; C – IV; D – I

Hint:

Always memorize crystal systems by constraints on (a, b, c) and angles (\(\alpha, \beta, \gamma\)); this makes matching questions direct and fast.

Answer 1

The Correct Option is B

Step 1: Understand crystal systems and their defining parameters.
Crystal systems are classified based on the relationship between edge lengths \(a, b, c\) and interfacial angles \(\alpha, \beta, \gamma\). Each system has a unique geometrical constraint that defines its unit cell symmetry. Matching requires identifying these constraints correctly for each system.

Step 2: Analyze Cubic system (A).
In a cubic system, all edges are equal and all angles are \(90^\circ\): \[ a = b = c,\quad \alpha = \beta = \gamma = 90^\circ \] This matches statement IV. Hence: \[ A \rightarrow IV \]

Step 3: Analyze Monoclinic system (B).
In a monoclinic system, all sides are unequal but two angles are right angles and one is not: \[ a \ne b \ne c,\quad \alpha = \gamma = 90^\circ,\quad \beta \ne 90^\circ \] This corresponds to statement III. Hence: \[ B \rightarrow III \]

Step 4: Analyze Tetragonal system (C).
In tetragonal system: \[ a = b \ne c,\quad \alpha = \beta = \gamma = 90^\circ \] This exactly matches statement II. Hence: \[ C \rightarrow II \]

Step 5: Analyze Triclinic system (D).
In triclinic system, all edges and angles are unequal: \[ a \ne b \ne c,\quad \alpha \ne \beta \ne \gamma \ne 90^\circ \] This matches statement I. Hence: \[ D \rightarrow I \]

Step 6: Final matching and conclusion.
Thus, \[ A \rightarrow IV,\quad B \rightarrow III,\quad C \rightarrow II,\quad D \rightarrow I \] Therefore, correct option is: \[ \boxed{(2)} \]