Civil Engineering
2025 · Paper 2
Take it one question at a time. Try an answer, then check your understanding.
Complete GATE CE 2025 Paper 2 overview, original pages and practice · Timed previous-paper practice
Questions 61–63 of 65. Imported answers require review unless explicitly marked reviewed.
Question 61
Open questionCENAT2 marksNeeds review
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).Ca
= 150 mg/L as CaCO
Mg
= 40 mg/L as CaCO
Fe
= 10 mg/L as CaCO
Na
= 50 mg/L as CaCO
K
= 10 mg/L as CaCO
CO
= 120 mg/L as CaCO
HCO
= 30 mg/L as CaCO
Cl
= 50 mg/L as CaCO
; Other anions were not analysed.Log in to check the answer
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Open questionCENAT2 marksNeeds review
A community generates 1 million litres/day (MLD) of wastewater. This wastewater is treated using activated sludge process (ASP). The working volume of the aeration tank of the ASP is 250 m
, and the biomass concentration in the tank is 3000 mg/L. Analyses results showed that a biomass concentration of 100 mg/L is present in the treated effluent from the secondary sedimentation tank of the ASP. Sludge wastage from the system is at a rate of 5000 L/day with a biomass concentration of 1000 mg/L. The system is in steady state condition.The biological sludge residence time (BSRT) of the system (in days) is ______ (round off to one decimal place).
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 63
Open questionCENAT2 marksNeeds review
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).Log in to check the answer
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