Question

Consider the following units for measurement of salinity in irrigation water A. \(1\) mhos/m \(=\) \(1\) Siemens/m (s/m) B. \(1\) millimhos/cm \(=\) \(1\) deciSiemens/m (dS/m) C. \(1\) EC \(\times 10^{-3} = 1\) millimhos \(\per\) cm D. \(1\) EC \(\times 10^{-6} = 1\) micromhos \(\per\) cm E. meq/l \(= 10 \times\) EC \(\times 10^3\) Choose the correct answer from the options given below:

• A. A, B, C Only
• B. B, C, D Only
• C. A, B, D Only
• D. A, B, E Only

Hint:

Important salinity unit conversions: \[ \boxed{ 1\ \text{mho} = 1\ \text{Siemens} } \] \[ \boxed{ 1\ \text{mmhos/cm} = 1\ \text{dS/m} } \] Remember:
• EC increases with dissolved salts
• Higher EC means higher salinity hazard

Answer 1

The Correct Option is C

Concept: Salinity of irrigation water is commonly measured using:
• Electrical conductivity (EC)
• Total dissolved salts
• Ionic concentration Since dissolved salts conduct electricity, electrical conductivity becomes a convenient measure of salinity. Common conductivity units include:
• mho
• Siemens (S)
• millimhos/cm
• deciSiemens/m
• micromhos/cm Several unit conversion relationships are used in irrigation engineering.

Step 1: Analyzing Statement A. Statement A says: \[ 1\ \text{mhos/m} = 1\ \text{Siemens/m} \] This statement is correct because: \[ \boxed{ 1\ \text{mho} = 1\ \text{Siemens} } \] The term mho is the older name for electrical conductance, while Siemens is the SI unit. Therefore: \[ \boxed{ 1\ \text{mho/m} = 1\ \text{S/m} } \] Hence: \[ \boxed{\text{Statement A is correct}} \]

Step 2: Analyzing Statement B. Statement B says: \[ 1\ \text{millimhos/cm} = 1\ \text{deciSiemens/m} \] This is a standard conductivity conversion relation. Because: \[ \boxed{ 1\ \text{mmhos/cm} = 1\ \text{dS/m} } \] Hence: \[ \boxed{\text{Statement B is correct}} \]

Step 3: Analyzing Statement C. Statement C says: \[ 1\ EC \times 10^{-3} = 1\ \text{millimhos/cm} \] This statement is incorrect. The relation is not properly expressed dimensionally. Standard relationships involve: \[ 1\ \text{dS/m} = 1\ \text{mmhos/cm} \] Thus Statement C is not a valid standard conversion. Hence: \[ \boxed{\text{Statement C is incorrect}} \]

Step 4: Analyzing Statement D. Statement D says: \[ 1\ EC \times 10^{-6} = 1\ \text{micromhos/cm} \] This corresponds to the conversion involving micromhos and conductivity scaling. Since: \[ \boxed{ 1\ \mu\text{mho/cm} } \] represents micro-level conductivity units, the statement is accepted as correct in irrigation engineering unit conversions. Hence: \[ \boxed{\text{Statement D is correct}} \]

Step 5: Analyzing Statement E. Statement E says: \[ \text{meq/l} = 10 \times EC \times 10^3 \] This expression is incorrect. There is no universal direct relation of this form between:
• meq/l
• electrical conductivity because conversion depends on ionic composition. Hence: \[ \boxed{\text{Statement E is incorrect}} \]

Step 6: Identifying correct statements. Correct statements are: \[ A,\; B,\; D \] Incorrect statements are: \[ C,\; E \] Thus the correct option becomes: \[ \boxed{ (C)\ A,\; B,\; D\ Only } \] Final Conclusion: The correct salinity measurement relations are: \[ \boxed{ A,\; B,\; D } \] Hence the correct answer is: \[ \boxed{ (C)\ A,\; B,\; D\ Only } \]