Question

Which one of the following instruments is used for the determination of exchangeable cations in soil?

• A. UV-VIS spectrophotometer
• B. Atomic absorption spectrophotometer
• C. Flame photometer
• D. Colorimeter

Hint:

Instrumentation for soil analysis:
- Flame photometer: Cations (Na, K, Ca).
- AAS: Trace metals.
- UV-VIS: Nitrate, phosphate.
- Colorimeter: Colorimetric analysis.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This question tests knowledge of analytical instruments used in soil analysis.

Step 2: Detailed Explanation:
A flame photometer (C) is used for the determination of exchangeable cations in soil.
It measures the concentration of cations such as Na$^+$, K$^+$, Ca$^{2+}$, and Li$^+$ by emission spectroscopy.
Other options:
- UV-VIS spectrophotometer (A): Used for measuring light absorption (e.g., nitrate, phosphate).
- Atomic absorption spectrophotometer (B): Used for trace metal analysis (e.g., Zn, Cu, Fe).
- Colorimeter (D): Used for colorimetric analysis.
Thus, the flame photometer is used for exchangeable cations.

Step 3: Final Answer:
Thus, the flame photometer is used for the determination of exchangeable cations, which corresponds to option (C).
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