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Current Affairs January 2024

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4

Plants produce carbohydrates from the CO2 present in the atmosphere by

A. Polymerisation

B. Photochemical reaction

C. Oxidation

D. None of these

Correct Answer :

B. Photochemical reaction


Related Questions

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4

__________ is the process of coating the surface of steel with aluminium oxide, thereby imparting it increased resistance to corrosion & oxidation upto a temperature of 700°C.

A. Veneering

B. Galvanising

C. Electroplating

D. Calorising

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4

Which of the following alloying elements is present in maximum percentage in high speed steel?

A. Molybdenum

B. Chromium

C. Tungsten

D. Vanadium

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4

The co-ordination number in simple cubic structure is

A. 4

B. 6

C. 8

D. 12

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4

Which of the following metals is the most prone to work hardening?

A. Brass

B. Aluminium

C. Copper

D. Lead

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4

Particle nature of cathode rays is proved due to the fact that they

A. Travel in a straight line

B. Get deflected by magnetic electric field

C. Produce fluorescence

D. Heat the exposed material

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4

Plasma is

A. A high temperature neutral gas

B. Nothing but ionised gas

C. A source of steady and highest controllable pressure

D. Formed at very low temperature

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4

Alloying elements present in Haynes stellite, which has superior performance than high speed steel, are:

A. Nickel, cobalt & chromium

B. Tungsten, chromium & cobalt

C. Manganese, chromium & cobalt

D. Tungsten, molybdenum & nickel

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4

Steel rods are normally used for concrete reinforcement because concrete and steel have almost equal

A. Tensile strength

B. Compressive strength

C. Young's modulus

D. Thermal co-efficient of expansion

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4

The emf of a Deniell cell Zn | Zn2+ || Cu2+ | Cu can be increased by

A. Decreasing the surface area of the electrodes

B. Increasing the concentration of zinc sulphate solution

C. Increasing the surface area of the electrodes

D. Increasing the concentration of copper sulphate solution

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4

Cassiterite is an ore of

A. Tin

B. Lead

C. Molybdenum

D. Chromium

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4

Change in volume of metals from absolute zero temperature to their melting points is

A. Almost same for all metals

B. Different for different metals

C. Less for low melting point metals

D. Less for high melting point metals

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4

Normalising of an object does not

A. Refine coarse grain structure obtained during hot working

B. Improve ductility

C. Improve yield strength

D. Improve mechanical properties

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4

Lead is added to 60:40 brass primarily to improve

A. Machinability

B. Corrosion resistance

C. Fluidity

D. Strength

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4

To improve the machinability of steel, it is generally subjected to

A. Spheroidising

B. Tempering

C. Normalising

D. Annealing

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4

For separating small pieces of metal from engine oil of a car, the best separating technique is the

A. Chromatography

B. Evaporation

C. Filtration

D. Fractional distillation

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4

Which of the following metals cannot be hot worked at room temperature?

A. Zinc

B. Nickel

C. Lead

D. Tin

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4

The size of the tetrahedral void in the closest packing of atoms is __________ that of the octahedral void.

A. Equal to

B. Greater than

C. Less than

D. Either (A), (B) or (C); depends on the size of atom

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4

Steel is welded using the __________ flame.

A. Carburising

B. Neutral

C. Oxidising

D. All (A), (B) & (C)

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4

Factor of safety is the ratio of the __________ stress to the working stress.

A. Tensile

B. Compressive

C. Yield

D. Bearing

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4

Energy to be supplied to the radioactive nucleus for the emission of a neutron is __________ MeV.

A. 0.8

B. 7.8

C. 200

D. 10000

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4

Use of water as a manometric liquid suffers from the disadvantage of its

A. Low vapour pressure

B. Corrosive nature

C. High vapour pressure

D. High boiling point

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4

Plants produce carbohydrates from the CO2 present in the atmosphere by

A. Polymerisation

B. Photochemical reaction

C. Oxidation

D. None of these

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4

__________ cannot increase the fatigue strength of a material.

A. Grain refining

B. Grain coarsening

C. Surface hardening

D. Shot peening

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4

Production of a hollow product by inflation of a tube or parison is called the __________ process.

A. Blow moulding

B. Calendaring

C. Extrusion

D. Injection

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4

Mild steel has __________ crystal lattice structure.

A. Face centred cubic (fcc)

B. Body centred cubic (bcc)

C. Orthorhombic

D. Cubic

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4

Highest cutting speed is achieved by the __________ tool material.

A. High speed steel

B. Carbide

C. Cast alloy

D. Plain carbon steel

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4

__________ is used as a material of construction for the blade of power saw.

A. Wrought iron

B. Stainless steel

C. Mild steel

D. High speed steel

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4

Broaching tools are usually made of

A. Cermets

B. High speed steel

C. Tungsten carbide

D. Stellite

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4

The delivery pressure of boiler feed water pump compared to the boiler steam pressure is

A. Same

B. Slightly less

C. Slightly more

D. Much more

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4

Regeneration of molecular sieve requires it to be heated to a temperature of about __________ °C.

A. 80-120

B. 200-300

C. 600-800

D. 1000-1100