The Solid State

At room temperature (298 K), Copper oxide ( ) behaves as a semiconductor, as its electrical conductivity increases with temperature, which is characteristic of semiconductors.

The structure of transition metals at normal temperature can vary based on temperature. The crystal structure of an element refers to the arrangement of atoms within the solid.
- Titanium (A): Titanium has a hcp (hexagonal close-packed) structure at room temperature.
- Vanadium (B): Vanadium has a bcc (body-centered cubic) structure at room temperature.
- Silver (C): Silver has a ccp (cubic close-packed) structure.
- Chromium (D): Chromium has a bcc structure at room temperature.
- Manganese (E): Manganese is unique in that it exhibits both bcc and ccp structures at different temperatures. At lower temperatures, it adopts a bcc structure, and at higher temperatures, it adopts a ccp structure.
Thus, the correct answer is (E) Manganese, which has both bcc and ccp structures at normal temperature.

Concept: Chemistry - Molarity. [ M=\frac{\text{moles of solute}}{\text{volume in litre}} ]
Step 1: Convert volume into litre. [ 250\text{ mL}=0.250\text{ L} ]
Step 2: Find moles required. [ \text{Moles}=M \times V=0.4 \times 0.250=0.1 ]
Step 3: Find mass of sodium acetate. [ \text{Mass}=\text{moles} \times \text{molar mass} ] [ =0.1 \times 82=8.2\text{ g} ]
Step 4: Final answer. [ \boxed{8.2\text{ g}} ]
Hence, correct option is (B).