GATE CE area:environmental-engineering PYQs & Answers — Page 3

Questions 21–30 of 110. Imported answers require independent review unless marked reviewed.

A compound has a general formula CₐHᵦO꜀Nᵈ and molecular weight 187. A 935 mg/l solution of the compound is prepared in distilled deionized water. The Total Organic Carbon (TOC) is measured as 360 mg/l (as C). The Chemical Oxygen Demand (COD) and the Total Kjeldahl Nitrogen (TKN) are determined as 600 mg/l (as O₂) and 140 mg/l (as N), respectively (as per the chemical equation given below). Which of the following options is/are CORRECT?

CₐHᵦO꜀Nᵈ + ((4a + b − 2c − 3d)/4) O₂ → aCO₂ + ((b − 3d)/2) H₂O + dNH₃

Atomic weight: C(12), H(1), O(16), N(14)

Your answerSelect all correct options. You can choose more than one.

a = 6

b = 7

c = 5

d = 3

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

The analyses results of a water sample are given below. The non-carbonate hardness of the water (in mg/L) as CaCO

is ______ (in integer).

= 150 mg/L as CaCO

= 40 mg/L as CaCO

= 10 mg/L as CaCO

= 50 mg/L as CaCO

= 10 mg/L as CaCO

= 120 mg/L as CaCO

HCO

= 30 mg/L as CaCO

= 50 mg/L as CaCO

; Other anions were not analysed.

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

A settling chamber is used for the removal of discrete particulate matter from air with following conditions. Horizontal velocity of air = 0.2 m/s; Temperature of air stream = 77°C; Specific gravity of particle to be removed = 2.65; Chamber length = 12 m; Chamber height = 2 m; Viscosity of air at 77°C = 2.1 x 10

kg/m.s; Acceleration due to gravity (g) = 9.81 m/s

; Density of air at 77°C =1.0 kg/m

; Assume the density of water as 1000 kg/m

and Laminar condition exists in the chamber.

The minimum size of particle that will be removed with 100% efficiency in the settling chamber (in

m) is ______ (round off to one decimal place).

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

What is the CORRECT match between the air pollutants and treatment techniques given in the table?

Air pollutants	Treatment techniques
P - NO₂	i - Flaring
Q - SO₂	ii - Cyclonic separator
R - CO	iii - Lime scrubbing
S - Particles	iv - NH₃ injection

Your answerChoose one option.

P-i, Q-ii, R-iii, S-iv

P-ii, Q-i, R-iv, S-iii

P-ii, Q-iii, R-iv, S-i

P-iv, Q-iii, R-i, S-ii

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Which one of the following products is NOT obtained in anaerobic decomposition of glucose?

Your answerChoose one option.

CO₂

CH₄

H₂S

H₂O

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

The primary air pollutant(s) is/are

Your answerSelect all correct options. You can choose more than one.

Sulphur dioxide

Lead

Ozone

Sulphuric acid

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

A hypothetical multimedia filter, consisting of anthracite particles (specific gravity: 1.50), silica sand (specific gravity: 2.60), and ilmenite sand (specific gravity: 4.20), is to be designed for treating water/wastewater. After backwashing, the particles should settle forming three layers: coarse anthracite particles at the top of the bed, silica sand in the middle, and small ilmenite sand particles at the bottom of the bed.

Assume (i) Slow discrete settling (Stoke’s law is applicable) (ii) All particles are spherical (iii) Diameter of silica sand particles is 0.20 mm

The CORRECT option fulfilling the diameter requirements for this filter media is

Your answerChoose one option.

diameter of anthracite particles is slightly less than 0.35 mm and diameter of ilmenite particles is slightly greater than 0.141 mm.

diameter of anthracite particles is slightly greater than 0.35 mm and diameter of ilmenite particles is slightly less than 0.141 mm.

diameter of anthracite particles is slightly less than 0.64 mm and diameter of ilmenite particles is slightly less than 0.10 mm.

diameter of anthracite particles is slightly greater than 0.64 mm and diameter of ilmenite particles is slightly less than 0.10 mm.

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

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:

Your answerChoose one option.

No compliance, as the corrected HCl emission is greater than the emission standard.

Compliance is there, as the corrected HCl emission is lesser than the emission standard.

Compliance is there, as there is no need to apply the correction since Oxygen is greater than 11% and HCl emission is lesser than the emission standard.

No compliance, as the Oxygen is greater than 11% in the flue gas.

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

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).

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

A circular settling tank is to be designed for primary treatment of sewage at a flow rate of 10 million liters/day. Assume a detention period of 2.0 hours and surface loading rate of 4000 liters/m

/day. The height (in meters) of the water column in the tank is ______________ (rounded off to 2 decimal places).

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

GATE CE area:environmental-engineering PYQs

Question 49

Question 61

Question 63

Question 25

Question 26

Question 31

Question 42

Question 43

Question 60

Question 60