The leaching solvent used in Baeyer's process for the purification of bauxite is
Ammonium hydroxide
Sodium carbonate
Sodium hydroxide
Ammonium carbonate
Correct Answer :
B. Sodium carbonate
Related Questions
Nickel is a __________ material.
Ferromagnetic
Semi-conductor
Paramagnetic
Ferroelectric
'Dikes' are low height walls made around the storage vessels meant for storing hazardous & inflammable material (e.g., petroleum products). Volume of dikes is equal to (where, V = volume of the storage vessel)
V
V/2
2V
3V
With increase in temperature, the electrical conductivity of semiconductors
Increases
Decreases
Remain constant
Either (A) or (B), depends on the type of semi-conductor
The boiling & freezing points on a newly defined temperature scale in degree 'D' are 400°D & 100°D respectively. The temperature reading corresponding to 60°C on this new temperature scale will be equal to __________ °D.
140
180
240
280
In chemical dehumidification of air
Both specific humidity & dry bulb temperature increases
Both specific humidity & dry bulb temperature decreases
Specific humidity decreases & dry bulb temperature increases
Specific humidity increases & dry bulb temperature decreases
Cassiterite is an ore of
Tin
Lead
Molybdenum
Chromium
Normalising of an object does not
Refine coarse grain structure obtained during hot working
Improve ductility
Improve yield strength
Improve mechanical properties
In case of condensers & evaporators operating under given terminal conditions, LMTD (logarithmic mean temperature difference) for counter flow as compared to that for parallel flow is
More
Less
Equal
Much more
Heat flow across a hollow sphere of inner radius 'r1' and outer radius 'r2' is directly proportional to
(r2 - r1)/r1. r2
r1. r2/(r2 - r1)
(r2 + r1)/r1. r2
r1. r2/(r2 + r1)
A reduction in thermal resistance during heat transfer does not occur in the
Convection heat transfer by stirring the fluid and cleaning the heating surface
Conduction heat transfer by reduction in the material thickness and increase in the thermal conductivity
Radiation heat transfer by increasing the temperature and reducing the emissivity
None of these
Gross national product (GNP) means the total value of __________ in a country.
Goods produced
Gold reserve
Earning of the citizens
Taxes paid
Which of the following materials has the maximum shrinkage allowance?
Brass
Cast iron
Lead
Aluminium alloy
__________ is the hardest material out of the following.
Boron carbide
Tungsten carbide
Hardened steel
Silicon carbide
The thermodynamic law, 
= constant, is not followed by the
Free expansion of an ideal gas
Adiabatic expansion of steam in turbine
Adiabatic compression of air
Ideal compression of air
Moist air is cooled along the line of constant __________ , when it is passed over a cold & dry cooling coil, such that no condensation occurs?
Enthalpy
Relative humidity
Wet bulb temperature
Dew point temperature
__________ iron is produced by the annealing of white cast iron.
Malleable
Nodular
Ductile
Grey
Desalination of water
Makes it potable
Makes it non-potable
Means distillation of water
None of these
Matte smelting is used in the extraction of
Lead
Zinc
Aluminium
Copper
Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity)
1/k
k
k2
1/k2
__________ can replace tungsten in high speed steel.
Chromium
Vanadium
Cobalt
Molybdenum
Routing in production, planning & control is concerned with the
Sequence of operation to be performed
Progress of work performed
Authorisation of work to be performed
Balancing of load on machines
The trace metal present in insulin is
Cu
Zn
Fe
Ni
Diameter of the rivet to be provided on a 20 mm. thick boiler plate will be __________ mm.
10
20
30
40
__________ of austenite decreases the hardenability in steel.
Fine grains
Coarse grains
Homogeneity
Dissolved elements (except cobalt)
Which of the following is not the commercial name of poly-methyl-methacrylate (PMMA)?
Styrofoam
Lucite
Perspex
Plexiglass
Silicon percentage in acid resistant cast iron is about
4
8
14
20
Lead is poured into the joint between two __________ pipes.
Mild steel
Concrete
Cast iron
Asbestos cement
Which of the following metals is not subjected to electrolytic refining/purification?
Copper
Zinc
Tin
Aluminium
What is the range of tempering temperature (°C) for most of the materials?
75-100
200-300
350-450
500-600
Solidification time of a molten metal in a casting is proportional to (where, V = volume of metal & A = its surface area; in the casting)
V/A
V/A2
V2/A
V2/A2