जल गुणवत्ता मूल्यांकन में कौन सा रासायनिक/जैव रासायनिक पैरामीटर जैविक प्रदूषण के स्तर को दर्शाता है?

Turbidity in water is measured on which standard scale?

Mudball formation in rapid sand filters is the result of:

In a water sample, if 2 mg of platinum cobalt salt is dissolved in 1 litre of distilled water, then the colour produced is equal to: