GATE 2020 CE (Set 1) question paper PDF and answer key

“Ivory towers” is the idiom for intellectual or academic isolation from practical, everyday concerns. It fits the criticism stated in the sentence.

Official accepted option: B.

“Voracious” describes an exceptionally eager or insatiable reader. “Precocious” concerns unusually early development; “wise” and “all-round” do not express the stated appetite for reading.

Official accepted option: C.

Label the top joints from left to right A, C, E, G and the lower joints B, D, F, with the load at D. At the unloaded end G, EG and FG are zero. Joint F then gives DF=EF=0; joint E gives CE=DE=0. Horizontal equilibrium at D gives BD=0. The member AB connects the two immovable supports; with no imposed support movement or initial strain, its axial extension and force are zero. Thus eight members carry zero force. The three nonzero members are AC, BC and CD. A stiffness calculation using the shown geometry is included in the audit code.

Official accepted option: C.

The total molar concentration is $P/(RT)$. Hence the chemical mole fraction is $(41.6\times10^{-6})RT/P$. Multiplying by $10^6$ gives $41.6(82.05\times10^{-6})(293)=1.00009$ ppm, which rounds to 1.0 ppm.

Official accepted interval: 0.9 to 1.1.

Convert the wastewater BOD₅ to ultimate BOD: $L_w=500/(1-e^{-0.3(5)})=643.6085$ mg/L. Immediately after mixing, $L_0=[5(30)+0.20L_w]/5.20=53.6003$ mg/L. The mixed velocity is $5.20/40=0.13$ m/s, and travel time is $3000/(0.13\times86400)=0.267094$ day. Remaining BOD is $L=L_0e^{-0.3t}=49.4730$ mg/L, or 49.47 mg/L. Using wastewater BOD₅ directly as ultimate BOD would be incorrect.

Official accepted interval: 49.00 to 50.00.