GATE CE format:nat PYQs & Answers — Page 50 — Exam Papers

Questions 491–495 of 495. Imported answers require independent review unless marked reviewed.

Topic practice 495 questionsPage 50 of 50

The analysis of a water sample produces the following results:

Ion	milligram per milli-equivalent for the ion	Concentration (mg/L)
Ca	20.0	60
Mg	12.2	36.6
Na	23.0	92
K	39.1	78.2
Cl	35.5	71
SO	48.0	72
HCO	61.0	122

The total hardness (in mg/L as CaCO

) of the water sample is

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Two wastewater streams A and B, having an identical ultimate BOD are getting mixed to form the stream C. The temperature of the stream A is 20°C and the temperature of the stream C is 10°C. It is given that • the 5-day BOD of the stream A measured at 20°C = 50 mg/l • BOD rate constant (base 10) at 20°C = 0.115 per day • temperature coefficient = 1.135 The 5-day BOD (in mg/l, up to one decimal place) of the stream C, calculated at 10°C, is ______.

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The radii of relative stiffness of the rigid pavements P and Q are denoted by

and

, respectively. The geometric and material properties of the concrete slab and underlying soil are given below:

Pavement	Length of Slab	Breadth of Slab	Thickness of Slab	Modulus of Elasticity	Poisson’s Ratio	Subgrade Reaction Modulus
			Concrete			Soil
P
Q

The ratio (up to one decimal place) of

is

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The wastewater having an organic concentration of 54 mg/l is flowing at a steady rate of 0.8 m³/day through a detention tank of dimensions 2 m × 4 m × 2 m. If the contents of the tank are well mixed and the decay constant is 0.1 per day, the outlet concentration (in mg/l, up to one decimal place) is ______.

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An observer standing on the deck of a ship just sees the top of a lighthouse. The top of the lighthouse is 40 m above the sea level and the height of the observer’s eye is 5 m above the sea level. The distance (in km, up to one decimal place) of the observer from the lighthouse is

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