Quality Characteristics Of Water Practice Questions

In a water sample, the concentrations of $Ca^{2+},Mg^{2+},$ and $HCO_3^{-}$ are 100 mg/L, 36 mg/L and 122 mg/L, respectively. The atomic masses of various elements are: Ca = 40, Mg = 24, H = 1, C = 12, O = 16. The total hardness and the temporary hardness in the water sample (in mg/L as $CaCO_3$ ) will be

A water sample is analyzed for coliform organisms by the multiple-tube fermentation method. The results of confirmed test are as follows:

The most probable number (MPN) of coliform organisms for the above results is to be obtained using the following MPN Index. The MPN of coliform organisms per 100 mL is

The internal $\left(d_{i}\right)$ and external $\left(d_{o}\right)$ diameters of a Shelby sampler are 48 mm and 52 mm, respectively. The area ratio $\left(A_{r}\right)$ of the sampler (in %,round off to two decimal palces) is _____________

Which one of the following is correct?

A water filtration unit is made of uniform-size sand particles of 0.4 mm diameter with a shape factor of 0.84 and specific gravity of 2.55. The depth of the filter bed is 0.70 m and the porosity is 0.35. The filter bed is to be expanded to a porosity of 0.65 by hydraulic backwash. In the terminal settling velocity of sand particles during backwash is 4.5 cm/s, the required backwash velocity is

A sample of water contain an organic compound $C_8H_{16}O_8$ at a concentration of $10^{-3}$ mol/litre. Given that the atomic weight of C = 12 g/mol, H = 1 g/mol, and O = 16 g/mol, the theoretical oxygen demand of water (in g of $O_2$ per litre, round off to two decimal places), is ___________

An amount of 35.67 mg HCI is added to distilled water and the total solution volume is made to one litre. The atomic weights of H and CI are 1 and 35.5, respectively. Neglecting the dissociation of water, the pH of the solution, is

A river has a flow of 1000 million litres per day (MLD), $BOD_5$ of 5 mg/litre and Dissolved Oxygen (DO) level of 8 mg/litre before receiving the wastewater discharge at a location. For the existing environmental conditions, the saturation DO level is 10 mg/litre in the river. Wastewater discharge of 100 MLD with the $BOD_5$ of 200 mg/litre and DO level of 2 mg/litre falls at that location. Assuming complete mixing of wastewater and river water, the immediate DO deficit (in mg/litre, round off to two decimal places), is _________.

The ion product of water ( $pK_w$ ) is 14. If a rain water sample has a pH of 5.6, the concentration of $OH^-$ in the sample (in $10^{-9}$ mol/litre, round off to one decimal place), is ________

Alkalinity of water, in equivalent/litre (eq/litre), is given by $\{HCO_3^-\}+2\{CO_3^{2-}\}+\{OH^-\}-\{H^+\}$ where, { } represents concentration in mol/litre. For a water sample, the concentration of $HCO_3^? = 2 \times 10^{-3}$ mol/litre, $CO_3^{2-} = 3.04 \times 10^{-4}$ mol/litre and the pH of water = 9.0. The atomic weights are : Ca = 40; C = 12; and O = 16. If the concentration of $OH^-$ and $H^+$ are NEGLECTED, the alkalinity of the water sample (in mg/litre as $CaCO_3$ ), is

Analysis of a water sample revealed that the sample contains the following species. $CO_3^{2-}, Na^{+}, H^{+}$ , $PO_4^{3-}, AI^{3+}, H_2CO_3$ , $CI^{-}, Ca^{2+},Mg^{2+}$ , $HCO_3^{-}, Fe^{2+}, OH^-$ Concentrationsof which of the species will be required to compute alkalinity?

As per IS 10500:2012, for drinking water in the absence of alternate source of water, the permissible limits for chloride and sulphate, in mg/L, respectively are

A water sample analysis data is given below. The carbonate hardness (expressed as mg/L of $CaCo_{3}$ , up to one decimal place) for the water sample is ______

The analysis of a water sample produces the following results: The total hardness (in mg/L as $CaCO_{3}$ ) of the water sample is _____

The hardness of a ground water sample was found to be 420 mg/L as $CaCO_{3}$ . A softener containing ion exchange resins was installed to reduce the total hardness to 75 mg/L as $CaCO_{3}$ before supplying to 4 households. Each household gets treated water at a rate of 540 L/day. If the efficiency of the softener is 100%, the bypass flow rate (expressed in L/day) is _____________.

Effluent from an industry 'A' has a pH of 4.2. The effluent from another industry 'B' has double the hydroxyl ( $OH^{-}$ ) ion concentration than the effluent from industry 'A'. pH of effluent from the industry 'B' will be ____________.

A sample of water has been analyzed for common ions and results are presented in the form of a bar diagram as shown. The non-carbonate hardness (expressed in mg/L as $CaCO_{3}$ ) of the sample is

A groundwater sample was found to contain 500 mg/L total dissolved solids (TDS). TDS (in %) present in the sample is ________.

Some of the nontoxic metals normally found in natural water are