Salinity Measurement Units Analysis

This question requires evaluating the correctness of different statements about units used for measuring salinity in irrigation water.

Statement A: $1 \text{ mhos/m} = 1 \text{ Siemens/m (s/m)}$

Analysis: The Siemens (S) is the standard SI unit for electrical conductance. The 'mho' was an older unit for conductance. They are equivalent: $1 \text{ mho} = 1 \text{ S}$.

Conclusion: Statement A is correct.

Statement B: $1 \text{ millimhos/cm} = 1 \text{ decisiemens/m (ds/m)}$

Analysis: This involves unit conversion:

• $1 \text{ dS/m} = 10^{-1} \text{ S/m}$
• $1 \text{ mS/cm} = 10^{-3} \text{ S/cm}$
• Since $1 \text{ cm} = 10^{-2} \text{ m}$, we have $1 \text{ S/cm} = 100 \text{ S/m}$.
• Substituting: $1 \text{ mS/cm} = 10^{-3} \times (100 \text{ S/m}) = 10^{-1} \text{ S/m} = 1 \text{ dS/m}$.
• As $1 \text{ mS/cm}$ is equivalent to $1 \text{ millimho/cm}$, the relationship holds.

Conclusion: Statement B is correct.

Statement C: $1 \text{ EC} \times 10^{-3} = 1 \text{ millimhos/cm}$

Analysis: Let EC represent the numerical value of Electrical Conductivity in dS/m. Then $1 \text{ EC} \times 10^{-3}$ would be $1 \text{ dS/m} \times 10^{-3} = 10^{-3} \text{ dS/m}$. However, $1 \text{ millimho/cm} = 1 \text{ mS/cm} = 1 \text{ dS/m}$. Since $10^{-3} \text{ dS/m} \neq 1 \text{ dS/m}$, the statement is incorrect.

Conclusion: Statement C is incorrect.

Statement D: $1 \text{ EC} \times 10^{-6} = 1 \text{ micromhos/cm}$

Analysis: We know that $1 \text{ dS/m} = 1000 \mu \text{mhos/cm}$. This implies $1 \mu \text{mho/cm} = 10^{-3} \text{ dS/m}$. If EC is in dS/m, then $1 \text{ EC} \times 10^{-6}$ (i.e., $1 \text{ dS/m} \times 10^{-6}$) equals $10^{-6} \text{ dS/m}$. This is not equal to $10^{-3} \text{ dS/m}$.

Conclusion: Statement D is incorrect.

Statement E: $\text{meq/l} = 10 \times \text{EC} \times 10^{3}$

Analysis: This statement presents an empirical formula used to estimate total dissolved salts in milliequivalents per liter (meq/l) from Electrical Conductivity (EC). Such approximate relationships are common in water quality assessments for irrigation. For the purpose of this question, this formula is considered a correct representation of such an approximation.

Conclusion: Statement E is considered correct in this context.

Final Answer Determination

Based on the analysis, statements A, B, and E are correct.

Therefore, the correct option includes only A, B, and E.