Heat and Mass Transfer Operations MCQs 2026

Fourier law of heat conduction states

1. Aflux proportional to pressure gradient✓
2. Bflux proportional to concentration gradient only✓
3. Cheat flux proportional to negative temperature gradient✓
4. Dflux independent of area✓

Newton law of cooling gives convective heat flux as

1. Ak ∂T/∂x only✓
2. Bh(T_surface − T_fluid)✓
3. CσεT⁴ only✓
4. Dρgh only✓

Nusselt number Nu is defined as

1. AρvL/μ✓
2. Bμ/ρD✓
3. CCpμ/k✓
4. DhL/k✓

Prandtl number Pr equals

1. AhL/k✓
2. BCpμ/k✓
3. CρvL/μ✓
4. Dk/ρCpL✓

Fick first law for diffusion is

1. AJ = h ΔT✓
2. BJ = k ∇T✓
3. CJ = f ΔP✓
4. DJ = −D dC/dx✓

Biot number assesses

1. Ainertia versus viscosity✓
2. Bmomentum versus diffusion in reactor✓
3. Cinternal conduction resistance versus surface convection resistance✓
4. Dpipe roughness only✓

Stefan-Boltzmann law for gray body includes emissivity as

1. Amultiplier on blackbody emission✓
2. Bdivisor on temperature✓
3. Cadditive constant to flux✓
4. Dreplacement for area✓

Overall heat transfer coefficient U accounts for

1. Aonly radiation always✓
2. Bseries resistances of convection, conduction and fouling✓
3. Conly pump head✓
4. Donly reaction rate✓

LMTD in heat exchangers is used when

1. Aboth fluids at same temperature always✓
2. Btemperature difference varies along exchanger length✓
3. Conly phase change in vacuum✓
4. Donly laminar pipe flow without heat✓

Mass transfer coefficient ky relates flux to

1. Adifference in mole fraction or concentration✓
2. Bonly pressure drop✓
3. Conly pipe friction✓
4. Donly shaft torque✓