GATE CH year:2025 PYQs & Answers — Page 7

Questions 61–65 of 65. Imported answers require independent review unless marked reviewed.

Topic practice 65 questionsPage 7 of 7

Methanol is produced by the reversible, gas-phase hydrogenation of carbon monoxide as

and

are charged to a reactor and the reaction proceeds to equilibrium at 453 K and 2 atm. The reaction equilibrium constant, which depends only on the temperature, is 1.68 at the reaction conditions. The mole fraction of

in the product is 0.4. Assuming ideal gas behaviour, the mole fraction of methanol in the product is ____ (rounded off to 2 decimal places).

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The block diagram of a series cascade control system (with time in minutes) is shown in the figure. For

min and

, the maximum value of

, below which the cascade control system is stable, is ____ (rounded off to the nearest integer).

Diagram for Chemical Engineering question 62

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It is proposed to install thermal insulation in a residence to save on the summer-monsoon season air-conditioning costs. The estimated yearly saving is 20 thousand rupees. The cost of installation of the insulation is 150 thousand rupees. The life of the insulation is 12 years. For a compound interest rate of 9% per annum, the minimum salvage value of the insulation for which the proposal is competitive, is ____ thousand rupees (rounded off to nearest integer).

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Consider the flowsheet in the figure for manufacturing

via the reaction

in an isothermal CSTR. The split in the separator is perfect so that the recycle stream is free of

and the product stream is pure

. Let

denote the mole fraction of species

(

) in the CSTR, which is operated in excess

with

. The reaction is first-order in

with the reaction rate

, where

kmol/(m

h).

Diagram for Chemical Engineering question 64

The reactor volume

in m

is to be optimized to minimize the cost objective

, where

is the recycle rate in kmol/h. For a product rate

kmol/h, the optimum value of

is ____ m

(rounded off to the nearest integer).

GIVEN:

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A wet solid of 100 kg containing 30 wt% moisture is to be dried to 2 wt% moisture in a tray dryer. The critical moisture content is 10 wt% and the equilibrium moisture content is 1 wt%. The drying rate during the constant rate period is 10 kg/(h m

). The drying curve in the falling rate period is linear. If the drying area is 5 m

, the time required for drying is ____ h (rounded off to 1 decimal place).

Note: All the moisture values given are on dry-solid basis.

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GATE CH year:2025 PYQs

Question 61

Question 62

Question 63

Question 64

Question 65