For assessing the compliance with the emissions standards of incineration plants, a correction needs to be applied to the measured concentrations of air pollutants. The emission standard (based on 11% Oxygen) for HCl is 50 mg/Nm³ and the measured concentrations of HCl and Oxygen in flue gas are 42 mg/Nm³ and 13%, respectively.

Assuming 21% Oxygen in air, the CORRECT statement is:

Activated carbon is used to remove a pollutant from wastewater in a mixed batch reactor, which follows first-order reaction kinetics.

At a reaction rate of 0.38 /day, the time (in days) required to remove the pollutant by 95% is _______________ (rounded off to 1 decimal place).

A water treatment plant treats 25 MLD water with a natural alkalinity of 4.0 mg/L (as CaCO₃). It is estimated that, during the coagulation of this water, 450 kg/day of calcium bicarbonate (Ca(HCO₃)₂) is required based on the alum dosage.

Consider the atomic weights as: Ca-40, H-1, C-12, O-16.

The quantity of pure quick lime, CaO (in kg) required for this process per day is _______ (rounded off to 2 decimal places).

The number of degrees of freedom for a natural open channel flow with a mobile bed is