In case of dry spinning of polymers, the polymer solution in a volatile solvent is forced through the spinnerates into a warm air chamber, where the solvent evaporates leaving behind the polymer in the filament form. Dry spinning is used for __________ fibres.

In case of wet spinning of polymers, the polymer solution is forced through spinnerates into, a coagulating bath to give a filament form. Wet spinning is not used in case of the __________ fibres.

A

Viscose rayon

B

Acrylic

C

Polyvinyl acetate

D

Saturated polyester

Melt spinning of polymers involves the forcing of polymer melt through spinnerettes (fine holes) into an atmosphere kept at a temperature lower than the melting point of the polymer, which causes the fine diameter polymer melt to harden into filaments. Melt spinning is not used in case of the __________ fibres.

A

Acrylic

B

Polyester

C

Nylon 6:6

D

Polypropylene

The vapor pressure of the solvent decreased by 10 mm Hg, when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent, if the decrease in vapor pressure of the solvent is required to be 20 mm Hg.?

A

0.2

B

0.1

C

0.4

D

0.6

Paper making polymers can be categorized as naturally occurring polymers, modified naturally occurring polymers, and synthetic polymers.

A

True

B

False

The bypass factor (B.P.F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil and td₃ = Dry bulb temperature of heating coil)

A

$$\frac{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}$$

B

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}$$

C

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$

D

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}$$

The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the cooling coil and td₃ = Dry bulb temperature of the cooling coil)

A

$$\frac{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$

B

$$\frac{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}$$

C

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$

D

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}$$

Children are in pursuit of a dog whose leash has broken. James is directly behind the dog. Ruby is behind James. Rachel is behind Ruby. Max is ahead of the dog walking down the street in the opposite direction. As the children and dog pass, Max turns around and joins the pursuit. He runs in behind Ruby. James runs faster and is alongside the dog on the left. Ruby runs faster and is alongside the dog on the right. Which child is directly behind the dog?

A

James

B

Ruby

C

Rachel

D

Max

S₁:Metals are today being replaced by polymers in many applications.
P :Above all, they are cheaper and easier to process making them a viable alternative to metals.
Q :Polymers are essentially a long chains of hydrocarbon molecules.
R :Today polymers as strong as metals have been developed.
S :These have replaced the traditional chromium-plated metallic bumpers in cars.
S₆:Many Indian Institutes of science and Technology run special programmes on polymer science.

The Proper sequence should be:

A

QRSP

B

RSQP

C

RQSP

D

QRPS

Oligomers react to form short chain polymers, then the short chained polymers react to form moderately long chain polymers. The number _________ can be predicted as a function of the extent of reaction.

A

Average DP

B

John DP

C

Pascal DP

D

Rankine DP

Sound waves travel at 350 m/s through warm air and at 3,500 m/s through brass. What happens to the wavelength of a 700 Hz acoustic wave as it enters brass from warm air?

A

It decreases by a factor of 20.

B

It decreases by a factor of 10.

C

It increases by a factor of 10.

D

The wavelength remains unchanged.

In case of dry spinning of polymers, the polymer solution in a volatile solvent is forced through the spinnerates into a warm air chamber, where the solvent evaporates leaving behind the polymer in the filament form. Dry spinning is used for __________ fibres.

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