In chromatography, a column is most efficient when it has which of the following plate heights?

• A. A variable plate height
• B. A small plate height
• C. A large plate height
• D. Plate height does not affect efficiency

Answer: (B)

Verified step by step guidance

1. Understand that in chromatography, the efficiency of a column is often described by the concept of 'plate height' (H), which is related to the number of theoretical plates (N) and the length of the column (L) by the equation \(H = \frac{L}{N}\).
2. Recognize that a smaller plate height means more theoretical plates per unit length, indicating better separation efficiency because the solute bands are narrower and more distinct.
3. Recall that a large plate height corresponds to fewer theoretical plates and broader solute bands, which reduces the resolution and efficiency of the column.
4. Note that a variable plate height is not ideal because it implies inconsistent separation performance along the column.
5. Conclude that the column is most efficient when it has a small plate height, as this maximizes the number of theoretical plates and improves separation quality.