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Right choice is (a) Sulphur

Easy explanation: The most COMMON POISONS, such as sulphur, have to be tolerated, it is possible to UTILIZE CATALYSTS that contain sulphur. The molybdenum sulphides are examples of catalysts of this type. Under proper temperature and pressure conditions, these materials are EFFECTIVE hydrogenation catalysts.

The correct option is (B) False

To explain: TWO FORMS of ADSORPTION are now recognized: PHYSICAL adsorption and chemisorption.

The correct answer is (b) High

The BEST explanation: These surface atoms, having VARYING degrees of unsaturation compared with the bulk metal or metal oxide, will STRONGLY adsorb other SUBSTANCES with which they may come in contact, and active catalysts usually have high absorptive powers.

Right choice is (c) Decrease reaction

The best I can explain: Although absorption is closely related to the successful performance of a catalyst, it MAY RUIN an ACTIVE, catalyst, because other SUBSTANCES called catalyst POISONS may be so strongly retained by these active atoms that the substance being hydrogenated can no longer reach the active or catalytic areas.

The correct OPTION is (B) Liquid

Easy EXPLANATION: The effect of the solubility of hydrogen in the REACTING substance obviously relates only to liquid-phase reactions.

Right answer is (C) Metals

Explanation: Hydrogenation CATALYSTS are solids consisting of metals and METAL OXIDES.

Correct option is (d) All of the mentioned

To EXPLAIN: The TIME necessary for a hydrogenation reaction may VARY from a few seconds to several HOUR, DEPENDING on the materials being hydrogenated, the catalyst, the temperature, and the pressure.

The correct answer is (c) Decreases

The BEST explanation: In general, then, increasing TEMPERATURE adversely affects the equilibrium position, so that the maximum ULTIMATE yield is decreased; but it affects favourably the speed of a reaction, so that in a given time a greater QUANTITY of product can be OBTAINED.

Correct choice is (a) Increases

To elaborate: PRESSURE, like temperature, can AFFECT the rate of reaction as well as the equilibrium position. The rate of reaction is GENERALLY increased by increasing pressure, because a gas phase is usually present, and increased pressure GIVES increased CONCENTRATION.

The correct answer is (b) False

Explanation: Temperature is one of the most important VARIABLES affecting a reaction. Practically every hydrogenation reaction can be reversed by increasing temperature. It becomes necessary, then, to work at as IOWA temperature as POSSIBLE where the rate of reaction will still be satisfactory. Whereas catalysts affect only the speed and COURSE of a reaction, temperature AFFECTS the equilibrium position, the speed, and the path, or course, of a reaction.

The correct CHOICE is (a) True

For EXPLANATION: Most HYDROGENATION reactions are REVERSIBLE reactions.

Correct option is (d) All of the mentioned

To elaborate: It is desirable to carry out such a reduction at lower temperatures for TWO PERTINENT reasons: (1) the equilibrium yield is better, (2) decomposition or side REACTIONS are less likely to be TROUBLESOME.

Correct ANSWER is (a) LOWER

To explain I WOULD say: The compound with the lower free ENERGY is the more STABLE of the two under the experimental conditions chosen.

The CORRECT choice is (b) Decreases

Explanation: An INCREASE of hydrogen pressure generally decreases SELECTIVELY and an increase of temperature APPEARS to increase it.

Correct OPTION is (b) PROCEEDS on own

Explanation: All SPONTANEOUS reactions, i.e., those PROCEEDING of their own accord and in the absence of any electrical INFLUENCES, such as magnetic or electrostatic forces, or various forms of radiation, are attended by a free-energy decrease.

Correct CHOICE is (d) All of the mentioned

The explanation: SELECTIVE hydrogenations are accomplished either by making the proper choice of catalyst, temperature, PRESSURE, and solvent (and thereby attaining a difference in REACTION rate) or by interrupting the reaction when the desired amount of hydrogen has been ABSORBED.

Correct answer is (a) Nickel

The EXPLANATION is: Phenol, polyphenols, and CRESOLS YIELD AROMATIC hydrocarbons on hydrogenolysis over nickel catalysts at TEMPERATURES above 250°C.

The correct choice is (b) False

To EXPLAIN: Lactones undergo hydrogenolysis to GIVE GLYCOLS, acids, or tetrahydrofurans.

The correct OPTION is (B) Nickel

Explanation: Carbon-Carbon Linkages. Such linkages are frequently cleaved by hydrogen in the PRESENCE of HYDROGENATION CATALYSTS.

Correct choice is (a) True

To EXPLAIN: Cyclic HYDROCARBONS CONTAINING five- and six-membered RINGS are stable and do not undergo change except the usual degradative decompositions at HIGHER temperatures.

Right option is (d) All of the mentioned

To explain I would say: Hydrogenolysis is analogous to the reactions commonly termed HYDROLYSIS, ALCOHOLYSIS, and AMMONOLYSIS which involve cleavage of a bond induced by the action of WATER, alcohol, or ammonia, respectively.

The correct option is (b) CLEAVAGE of MOLECULE

Explanation: The term HYDROGENOLYSIS is a more EXACT expression than destructive of HYDROGENATION and refers particularly to cleavages in a molecule associated with the addition of hydrogen.

Correct choice is (a) True

For explanation: Aldehydes are reduced more rapidly than ketones, ALTHOUGH there are numerous EXAMPLES in which both aldehydes and ketones undergo reduction at room TEMPERATURE and at only a few atmospheres of hydrogen pressure in the presence of platinum or palladium CATALYSTS.

Right CHOICE is (c) Nickel

Easy explanation: Nickel is the most widely used CATALYST for hydrogenating AROMATIC NUCLEI, other catalysts such as platinum oxide and rhodium also are useful.

The correct answer is (B) False

To elaborate: The catalytic reduction of aromatics may be carried out either in the vapour phase at atmospheric pressure or in the liquid phase at hydrogen PRESSURES or 100-200 ATM.

The correct option is (a) Saturated

To explain I would say: Diolefins, compounds CONTAINING such LINKAGES undergo CATALYTIC hydrogenation to GIVE the corresponding saturated hydrocarbons.

The correct answer is (c) 18°C0

The EXPLANATION is: Aromatics, such COMPOUNDS GENERALLY require temperatures above 180°C for complete HYDROGENATION over nickel catalysts.

Correct answer is (d) All of the mentioned

Explanation: Polybutadiene may be hydrogenated over nickel catalyst at 260°C to hydrorubbers (Hydropol) of VARIOUS degrees of unsaturation. These rubbers have outstanding PROPERTIES as thermoplastics, especially as to low temperature properties, oil resistance, and tensile STRENGTH.

The CORRECT choice is (b) Higher

To ELABORATE: Higher-molecular-weight olefins are GENERALLY hydrogenated in the liquid phase unless their volatility is SUFFICIENT at the temperature of hydrogenation (150-200°C), in which case the reaction MAY be conducted in the vapour phase.

Right OPTION is (d) All of the mentioned

Explanation: COMPOUNDS of this class readily undergo CATALYTIC hydrogenation, usually in the presence of a NICKEL or nickel-containing catalyst and sometimes with platinum or palladium CATALYSTS.

Correct OPTION is (b) Catalyst used

Explanation: Selective hydrogenation of the acetylene to ethylene is accomplished by passing the mixture, which ALSO CONTAINS 10-35 per CENT of hydrogen, over a catalyst at a temperature RANGING from 200-315°C and at pressures of 45-155 psig.

Right ANSWER is (c) Hydrogen analysis

The explanation is: The mass spectrometer is an excellent method for analysing for hydrogen either in SIMPLE or complex mixtures. The majority of instruments USED for analysing for hydrogen are based on the THERMAL conductivity of the mixture in which hydrogen is PRESENT.

Right choice is (b) 1:3

For explanation I would say: The nuclear SPINS MAY be either parallel or antiparallel, these two forms have been designated “ortho” and “PARA,” respectively. At normal conditions a RATIO of ortho: para of about 3:1 exists. At low temperature the equilibrium is on the side of para-hydrogen.

The correct answer is (B) Reduces

To elaborate: With embrittlement and the removal of CARBON, the tensile strength of the STEEL is greatly reduced.

The CORRECT answer is (b) False

The explanation: Hydrogen at ELEVATED temperatures and pressures in contact with ORDINARY CARBON steels is particularly CORROSIVE.

The correct CHOICE is (b) Prevents explosion

Best explanation: All apparatus and lines should be CAREFULLY purged by an inert gas such as NITROGEN, carbon dioxide, or flue gases not containing OXYGEN, before hydrogen is ADMITTED to prevent any chances for explosion.

Correct choice is (d) All of the mentioned

To EXPLAIN: A leak not only means a loss of hydrogen but is, in addition, a decided HAZARD because of the INFLAMMABILITY and very WIDE explosive limits that hydrogen possesses. These limits are much WIDER than for most gases.

Right OPTION is (a) True

Best explanation: it is the lightest gas, it will diffuse or LEAK where other heavier gases will not, PARTICULARLY at HIGH pressure.

Right answer is (a) DIFFERENCE in Boiling point

The explanation: Liquefaction is a physical process of PURIFICATION based on the difference in boiling points of the COMPONENTS of the GAS when LIQUEFIED.