Fusion zone in the electric furnace used for reduction of phosphate rock to elemental phosphorous is maintained at __________ °C.

Yield of elemental phosphorous from rock phosphate is about __________ percent.

A

1-2

B

15-25

C

40-45

D

60-65

A mixture of phosphate rock __________ is heated in an electric furnace to produce phosphorous.

A

Salt & coke

B

Sand & coke

C

And coke

D

And sand

Electric furnace method for production of phosphorous uses phosphate rock

A

And phosphoric acid

B

And coke

C

And sulphuric acid

D

Silica and coke

Conversion of yellow phosphorous to red phosphorous is done by heating it in covered retorts at __________ °C in absence of air.

A

50-80

B

250-400

C

1000-1200

D

800-900

The most stable allotropic form of phosphorous is the __________ phosphorous.

A

White

B

Black

C

Yellow

D

Red

Heating a mixture of phosphate rock, coke and sand in an electric furnace produces

A

Phosphoric acid

B

Ammonium phosphate

C

Phosphorous

D

Superphosphate

Red phosphorous is changed into white phosphorous by

A

Heating in presence of light

B

Melting under pressure

C

Vaporisation followed by condensation

D

None of these

Both white phosphorous as well as red phosphorous

A

Are soluble in CS₂

B

Burns when heated in air

C

Reacts with hot caustic soda solution to give phosphine

D

All of the above

An electric furnace producing heat by means of an electric arc struck between each of three electrodes and the charge is called __________ furnace.

A

Resistance

B

Arc

C

Low frequency induction

D

None of these

Low grade phosphate rock can be used in electrical furnace, because

A

Of the better CaO/SiO₂ balance for slag formation

B

CaO content is less

C

It is cheap

D

It produces low cost product

Fusion zone in the electric furnace used for reduction of phosphate rock to elemental phosphorous is maintained at __________ °C.

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