Chemical Engineering Basics

A. Filmwise condensation gives a lower heat transfer rate than the dropwise condensation
B. Suitable coating or vapour additive is used to promote film wise condensation
C. If a condensing liquid does not wet the surface dropwise, even then condensation will take
place on it
D. Reynolds number of condensing liquid is based on its mass flow rate

A. Hot worked materials are subjected to annealing to remove internal stresses
B. Annealing of steel hardens it slightly
C. Normalising of a material induces stresses
D. Tempering of a material improves ductility & toughness but reduces hardness & brittleness

A. Seam welding, projection welding & spot welding are the classification of electrical resistance
welding
B. Electrode tip in spot welding is of copper and the tip diameter should be equal to t (where, t =
plate thickness to be welded)
C. In spot welding, two pieces to be joined are overlapped and placed between two electrodes
D. Mild steel sheet cannot be spot welded

A. Lead can creep under its own weight at room temperature
B. The electrical conductivity of gold is considerably reduced by alloying additions due to the
decrease in electron movement
C. Recrystallisation temperature decreases with decrease in strain in a cold worked metal
D. With increase in temperature, the electrical conductivity of intrinsic semi-conductor will

A. Both annealing and normalising release the internal stresses of the material besides improving
the mechanical properties
B. Low carbon steel does not respond to the heat treatment for hardening of the material, hence it
is subjected to case hardening or surface hardening processes like cyaniding, carburising,
nitriding etc., which produces high carbon outer layers resulting in increase of surface
hardness
C. Induction hardening and flame hardening techniques are also used for surface hardening
D. Martempering of a material is a hardening process

A. A ferromagnetic material becomes paramagnetic above the ‘Curie temperature’
B. Permanent magnets are made of hard materials, whereas electromagnets require soft magnetic
materials
C. Soft magnetic materials (e.g., pure iron) have higher permeability and low hysterisis loss and
coercive forces
D. Tungsten steel and alnico are not hard magnetic materials

A. Copper is the metal having the highest electronic conductivity
B. Hardenability & Weldability of metals are inversely related
C. Covalent bonding formed by sharing of electrons is present in all semi-conductor materials
D. Glass transition temperature applies to ‘polymers’ but not to ‘glasses’

A. Decreases with increase in strain hardening tendencies
B. Decreases with increase in hardness, in general
C. Depend on the composition, microstructure and physical & mechanical properties
D. Decreases with increases in tensile strength & decrease in grain size

A. Reduces the upper shelf energy
B. Increasing the ductility transition temperature
C. Decreases brittleness
D. Decreases hardness

A. Carbon
B. Manganese
C. Both A nor B
D. Neither A nor B