Explanation:

- The cube is hollow, closed, and has a side of 10 cm.

- Volume of cube = 10 cm × 10 cm × 10 cm = 1000 cm³.

- Weight of cube = 200 gm.

- Density of water = 1 gm/cm³.

- Cube floats, so weight of water displaced = weight of cube.

- Let x be the height submerged.

- Volume submerged = 10 × 10 × x = 100x cm³.

- Weight of water displaced = 100x gm.

- Set 100x = 200 gm ? x = 2 cm.

- Option 3: 2 cm is the correct answer.