Water Quality Parameters And Measurement

(A) Estimated organisms are gram negative:
The MPN method is often used to estimate the number of coliform bacteria, which are typically gram-negative organisms, in water samples. (B) Assumption of Poisson distribution:
MPN estimation is based on the Poisson distribution because it models the likelihood of rare events (like the presence of microorganisms) occurring in a sample. (C) Measures exact number of microorganisms:
The MPN method does not give an exact count of microorganisms. It provides an estimate of the number of organisms, hence it is a probabilistic method, not an exact measurement. (D) Quantification of pathogenic virus:
While the MPN method can estimate the number of microorganisms, it is also used to quantify specific pathogens, such as coliforms, which may include pathogenic viruses. Final Answer:

The Sodium Adsorption Ratio (SAR) is used to assess the suitability of water for irrigation purposes. The formula for SAR is: Where:
- is the concentration of sodium in the water (in mg/L),
- is the concentration of calcium in the water (in mg/L),
- is the concentration of magnesium in the water (in mg/L).
First, we convert the given concentrations into milliequivalents per liter (meq/L) using the following equation: Let's calculate each ion's concentration in meq/L: Now, we substitute the values into the SAR formula: Thus, the SAR of the water sample is 2.83. Final Answer: \boxed{(A) 2.83}