Which one of the following statements is not correct? Vulcanisation of rubber makes it - (1) soft and flexible (2) strong and hard (3) chemical resistant (4) withstand higher temperatures

Which one of the following statements is not correct? Vulcanisation of rubber makes it - (1) soft and flexible (2) strong and hard (3) chemical resistant (4) withstand higher temperatures
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(1) soft and flexible Explanation: In order to give more strength and more elasticity, natural rubber is heated with sulphur or sulphur compounds at 150°C temperature. Vulcanized rubber has good tensile strength. The working temperature of vulcanized rubber is enhanced up to 100°C. It has good resistance to organic solvents.
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Which one of the following statements is not correct? Vulcanisation of rubber makes it (1) soft and flexible (2) strong and hard (3) chemical resistant (4) withstand higher temperatures

Description : Which one of the following statements is not correct? Vulcanisation of rubber makes it (1) soft and flexible (2) strong and hard (3) chemical resistant (4) withstand higher temperatures

Last Answer : soft and flexible

Which of the following statements is correct? (a) Sporopollenin can be degraded by enzymes. (b) Sporopollenin is made up of inorganic materials. (c) Sporopollenin can withstand high temperatures as well as strong acids and alkalis. (d) Sporopollenin can withstand high temperatures but not strong acids.

Description : Which of the following statements is correct? (a) Sporopollenin can be degraded by enzymes. (b) Sporopollenin is made up of inorganic materials. (c) Sporopollenin can withstand high temperatures ... strong acids and alkalis. (d) Sporopollenin can withstand high temperatures but not strong acids.

Last Answer : (c) Sporopollenin can withstand high temperatures as well as strong acids and alkalis

Vulcanisation of raw rubber makes it (A) Soft (B) Less elastic (C) Plastic (D) Tacky

Description : Vulcanisation of raw rubber makes it (A) Soft (B) Less elastic (C) Plastic (D) Tacky

Last Answer : (B) Less elastic

(4) Liquid Hydrogen + Liquid Oxygen Explanation: LOX and liquid hydrogen, used in the Space Shuttle orbiter, the Centaur upper stage of the Atlas V, Saturn V upper stages, the newer Delta IV rocket, the H-IIA rocket, and most stages of the European Ariane rockets. Liquid fueled rocicets have higher specific impulse than solid rockets and are capable of being throttled, shut down, and restarted. Only the combustion chamber of a liquid fueled rocket needs to withstand high combustion pressures and temperatures and they can be regeneratively cooled by the liquid propellant.

Description : (4) Liquid Hydrogen + Liquid Oxygen Explanation: LOX and liquid hydrogen, used in the Space Shuttle orbiter, the Centaur upper stage of the Atlas V, Saturn V upper stages, the ... to withstand high combustion pressures and temperatures and they can be regeneratively cooled by the liquid propellant.

Last Answer : The BOD values of water indicate the (1) amount of organic debris (2) amount of oxygen used for biochemical oxidation (3) amount of oxygen used for biochemical reduction (4) amount of ozone used for biochemical oxidation

In vulcanisation process, rubber can be hardened by adding - (1) Nitrogen (2) Silicon (3) Sulphur (4) Alcohol

Description : In vulcanisation process, rubber can be hardened by adding - (1) Nitrogen (2) Silicon (3) Sulphur (4) Alcohol

Last Answer : (3) Sulphur Explanation: In order to give more strength and more elasticity, natural rubber is heated with sulphur or sulphur compounds at 150°C temperature. Vulcanized rubber has good tensile strength.

In vulcanisation process, rubber can be hardened by adding (1) Nitrogen (2) Silicon (3) Sulphur (4) Alcohol

Description : In vulcanisation process, rubber can be hardened by adding (1) Nitrogen (2) Silicon (3) Sulphur (4) Alcohol

Last Answer : Sulphur

Which of the following metals is used in Space Crafts to withstand high temperatures? (1) Fe (2) Ti (3) Ni (4) Pb

Description : Which of the following metals is used in Space Crafts to withstand high temperatures? (1) Fe (2) Ti (3) Ni (4) Pb

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Which of the following metals is used in Space Crafts to withstand high temperatures ? (1) Fe (2) Ti (3) Ni (4) Pb

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In vulcanisation, with which the natural rubber is heated? -Do You Know?

Description : In vulcanisation, with which the natural rubber is heated? -Do You Know?

Last Answer : answer:

In vulcanisation of rubber,

Description : In vulcanisation of rubber,

Last Answer : In vulcanisation of rubber, A. sulphur reacts to form new compound B. sulphur cross-links are ... layer over rubber D. all the statements are correct

In vulcanisation, with which the natural rubber is heated?

Description : In vulcanisation, with which the natural rubber is heated?

Last Answer : Sulphur

The process involved in converting rubber into a thin sheet or coating it on fabric is called (A) Extrusion (B) Mastication (C) Calendaring (D) Vulcanisation

Description : The process involved in converting rubber into a thin sheet or coating it on fabric is called (A) Extrusion (B) Mastication (C) Calendaring (D) Vulcanisation

Last Answer : (C) Calendaring

Vulcanisation of rubber does not increase its (A) Softness (B) Oxidation resistance (C) Weight & strength (D) Elasticity & water solubility

Description : Vulcanisation of rubber does not increase its (A) Softness (B) Oxidation resistance (C) Weight & strength (D) Elasticity & water solubility

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Vulcanisation of rubber does not increase its (A) Elasticity(B) Plasticity(C) Ductility(D) None of these

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Vulcanisation of rubber (A) Decreases its tensile strength (B) Increases its ozone & oxygen reactivity (C) Increases its oil & solvent resistance (D) Converts its plasticity into elasticity

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Peptizers like aromatic mercaptans (e.g. thiophenes) are added in rubber to (A) Protect rubber goods from attack by oxygen & ozone present in the atmosphere (B) Reduce its viscosity to permit easier processing (C) Reduce the time of vulcanisation and quantity of vulcanising agent (D) Increase its viscosity

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Most commonly used rubber vulcanisation agent is (A) Sulphur (B) Bromine (C) Platinum (D) Alumina

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Vulcanisation of rubber decreases its (A) Tensile strength (B) Resistance to organic solvents (C) Tackiness (D) Working temperature range

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Fillers such as zinc oxide and carbon black are added to the crude natural rubber before vulcanisation in order to improve its (A) Elasticity (B) Strength (C) Plasticity (D) Weathering characteristics

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Vulcanisation of rubber (A) Decreases its tensile strength (B) Increases its ozone & oxygen reactivity (C) Increases its oil & solvent resistance (D) Converts its plasticity into elasticity

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The process involved in converting rubber into a thin sheet or coating it on fabric is called (A) Extrusion (B) Mastication (C) Calendaring (D) Vulcanisation

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Ceramic remunerators can withstand temperatures up to: a) 600 oC b) 1300 oC c) 1700oC d) 950oC

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The lintels are preferred to arches because (A) Arches require more headroom to span the openings like doors, windows etc. (B) Arches require strong abutments to withstand arch thrust (C) Arches are difficult in construction (D) All of the abo

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Which of the following statements regarding evacuated tube collectors (ETC) are true? i) ETC is used for high temperatures upto 150oC ii) because of use of vacuum between two concentric glass tube, higher amount of heat is retained in ETC iii) heat loss due to conduction back to atmosphere from ETC is high iv) performance of evacuated tube is highly dependent upon the ambient temperature i & iii b) ii & iii c) i & iv d) i & ii

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Flexible foam (for mattresses) are usually made of (A) PVC (B) Silicone rubber (C) Polyurethanes (D) Polyamides

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Adhesive tape to affix rubber to carpet in high temperatures?

Description : Adhesive tape to affix rubber to carpet in high temperatures?

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Pick out the wrong statement. (A) A ferromagnetic material becomes paramagnetic above the 'Curie temperature' (B) Permanent magnets are made of hard materials, whereas electromagnets require soft magnetic materials (C) Soft magnetic materials (e.g., pure iron) have higher permeability and low hysterisis loss and coercive forces (D) Tungsten steel and alnico are not hard magnetic materials

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Last Answer : Option D

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Description : The substance that is added to make natural rubber strong and more bouncy is – (1) Polythene (2) Sponge (3) Sulphur (4) Chlorine

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The substance that is added to make natural rubber strong and more bouncy is (1) Polythene (2) Sponge (3) Sulphur (4) Chlorine

Description : The substance that is added to make natural rubber strong and more bouncy is (1) Polythene (2) Sponge (3) Sulphur (4) Chlorine

Last Answer : Sulphur

Which characteristic of the Sun primarily determines the orbits of planets in our solar system A Large volume B Strong gravitational field C Mostly made of hydrogen D High surface temperatures?

Description : Which characteristic of the Sun primarily determines the orbits of planets in our solar system A Large volume B Strong gravitational field C Mostly made of hydrogen D High surface temperatures?

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Chilled iron castings are (A) Easily machinable (B) Soft on surface(C) Highly wear resistant(D) None of these

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Bakeries use yeast in breadmaking because it (1) makes the bread hard (2) makes the bread soft and spongy (3) enhances the food values (4) keeps the bread fresh

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Last Answer : makes the bread soft and spongy

Consider the following statements S1 and S2 : S1 : A hard handover is one in which the channel in the source cell is retained and used for a while in parallel with the channel in the target cell. S2 : A soft handover is one in which the channel in the source cell is released and only then the channel in the target cell is engaged. (A) S1 is true and S2 is not true. (B) S1 is not true and S2 is true. (C) Both S1 and S2 are true. (D) Both S1 and S2 are not true.

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Last Answer : (D) Both S1 and S2 are not true.

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Last Answer : Ans:(a)

Three of the following statements about enzymes are correct and one is wrong. Which one is wrong? (a) Enzymes require optimum pH for maximal activity. (b) Enzymes are denatured at high temperature but in certain exceptional organisms they are effective even at temperatures 80° - 90°C. (c) Enzymes are highly specific. (d) Most enzymes are proteins but some are lipids.

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