Heat treatment alters the properties of steel due to
chemical reaction on heating
partial rusting
change in the residual energy
change in the lattice structure due to differential rate of cooling
Match List-I withList-II and select the correct answer using the codes given below.
List I | List II |
A. Rinnmann's green | 1. Cu(CH3COO)2.Cu(OH)2 |
B. Verdigris | 2. HgCl2 |
C. Corrosive sublimate | 3. CoZnO2 |
D. Lithopone | 4. ZnS + BaSO4 |
Codes
A B C D
1 3 4 2
A B C D
3 1 2 4
A B C D
2 1 4 3
A B C D
1 2 3 4
In Goldschmidt aluminothermic process, thermite contains
3 parts of Al2O3 and 4 parts of Al
3 parts of Fe2O3 and 2 parts of Al
3 parts of Fe2O3 and 1 part of Al
1 part of Fe2O3 ad 1 part of Al
In the electrolytic method of obtaining aluminium from purified bauxite, cryolite is added to the charge in order to
minimise the heat loss due to radiation
protect aluminium produced from oxygen
dissolve bauxite and render it conductor of electricity
lower the melting point of bauxite.
Identify the reaction that does not take place during the smelting process of copper extraction
2FeS + 3O2 → 2FeO + 2SO2 ↑
Cu2O + FeS → Cu2S + FeO
2Cu2S + 3O2 → 2Cu2O + 2SO2 ↑
FeO + SiO2 → FeSiO3
Railway wagon axles are made by heating iron rods embedded in charcoal powder. This process is known as
tempering
case hardening
sherardising
annealing
In the electrothermal process, the compound displaced by silica from calcium phosphate is
calcium phosphide
phosphine
phosphorus
phosphorus pentoxide
D.
phosphorus pentoxide
In electrothermal process, silica is heated with calcium phosphate when phosphorus pentoxide is obtained. It is then reduced by coke in electric furnace to get white phosphorus.
2Ca3(PO4)2 + 6SiO2 6CaSiO3 + P4O10
P4O10 + 10C P4 + 10CO
In froth floatation process for the purification of ores, the particles of ore float because
their surface is not easily wetted by water
they are light
they are insoluble
they bear electrostatic charge