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Correct answer is (d) All of the mentioned

For EXPLANATION: The freezing-point depression, vapour-pressure drop, and boiling-point elevation of a liquid CAUSED by the presence of a DISSOLVED solute are a set of closely related phenomena which arise because of the requirements of thermodynamic EQUILIBRIUM between two phases.

The correct choice is (c) Free-radical

To explain I would SAY: The kinetics of ionic polymerization share some common principles with that of the free-radical REACTION. Both are BASED on the basic steps of INITIATION, propagation, termination, and chain transfer, and in both the ultimate AVERAGE molecular weight depends on the ratio of the reaction rates of propagation and termination.

Correct answer is (B) Propagation/ Termination

Explanation: The degree of polymerization of the polymer is OBTAINED from the ratio of the propagation reaction to that of termination, or the ratio of the propagation reaction to that of initiation, SINCE in the STEADY state the initiation and termination rates are EQUAL.

The correct choice is (a) True

For EXPLANATION: An important parameter in all polycondensations is the “extent of REACTION,” i.e., the fraction of the REACTIVE groups which have reacted up to a SPECIFIED TIME t.

Correct choice is (c) All of the mentioned

Best EXPLANATION: The principal feature of a polycondensation are: (1) that all the INTERMEDIATE SPECIES are STABLE molecules and (2) that the rate of condensation is independent of the DEGREE of polymerization, Le., the reactivity of the functional groups is independent of the molecular weight of the molecule to which it is attached.

The correct choice is (c) Suspension

The explanation is: Pearl (Suspension) Polymerization. The method of EMULSION polymerization has PROVED highly efficient for large-scale production of polymers of HIGH AVERAGE MOLECULAR weight.

The correct option is (b) Heat control

The explanation is: The disadvantage of a continuous and ELABORATE heat control, which is necessary in BULK polymerization, is completely OVERCOME if the monomers are dissolved in suitable solvents and the POLYMERIZATIONS carried out in solution.

Right OPTION is (d) All of the mentioned

Easy explanation: Thus the nature of the solvent and the concentration of the MONOMER are the DETERMINING factors for the progress of the polymerization at a certain TEMPERATURE, which progress, however, NEVER reaches the speed of a bulk polymerization.

Correct OPTION is (a) True

To EXPLAIN: During emulsion POLYMERIZATION under the influence of heat and APPROPRIATE catalysts, the average particle size decreases to about one-tenth of its starting size, and the polymer is usually obtained in the FORM of a very stable emulsion called a latex.

Correct choice is (a) True

For explanation I would say: The ease of POLYMERIZATION INCREASES with the AMOUNT of unsaturation and that CONJUGATION or ACCUMULATION of double bonds increases their reactivity.

Right option is (a) Yes

To explain I would say: Whether or not an active center can be formed, i.e., whether or not an unsaturated molecule is suitable for addition POLYMERIZATIONS DEPENDS on a number of factors. In the first place, the energy necessary to open one of the two LINKS of an aliphatic double bond depends upon the nature of the two ATOMS that are linked together by it, for instance, C=C or C=O. The electronic configurations of each of these atoms and the distances between them influence the DISSOCIATION energy of the double or triple bond.

Right answer is (a) Substituents on the atoms

Explanation: The energy required to activate the BOND is influenced by TWO more factors: (1) the substituents on the atoms which form the multiple bond and (2) the presence of conjugated or cumulated multiple BONDS.

The correct OPTION is (c) Low

Best explanation: Polycondensation proceeds FUNDAMENTALLY in the same manner as CONDENSATIONS between low-molecular-weight SUBSTANCES.

The correct choice is (a) True

Easiest explanation: During the ADDITION reaction, no stable compounds are formed because the intermediates are comparatively short-lived RADICALS or ions. The FORMATION of the polymer chain is usually accomplished in a fraction of a second and in one single sweep. Polymerization at the double bond is a TYPICAL addition reaction of this type.

Right answer is (b) CONDENSATION reaction

Easy explanation: The POLYMER formation in condensation polymerization PROCEEDS stepwise, the various intermediates, dimer, trimer, etc., existing as stable molecules until the next reaction step. Small molecules, USUALLY WATER, are split off at each step of the reaction.

Correct option is (a) Condensation reaction

Easiest EXPLANATION: POLYMERIZATION reactions are EITHER condensation reactions or ADDITION reactions.

The correct option is (c) Both DOUBLE and TRIPLE bond

To EXPLAIN I WOULD say: The bifunctionality is exhibited by a large group of MOLECULES containing double or triple bonds.

The correct CHOICE is (B) Two or more reactive

Best EXPLANATION: A molecule is called bi- or polyfunctional if two or more reactive or functional groups either are present at the beginning of the REACTION or APPEAR in the course of it.

The CORRECT ANSWER is (a) FORMATION of POLYMER

Easiest explanation: The concept of polyfunctionality of a molecule as a REQUIREMENT for the formation of polymer.

Right choice is (d) All of the mentioned

Easy explanation: Large molecular COMPLEXES can be BUILT in two possible ways: either by an association of small molecules by meaning of secondary bonds (van der Waals FORCES, etc.) or by CONTINUOUS chemical reactions between small molecules, thus establishing strong chemical bonds between them.

The correct answer is (c) Insoluble and decomposes

Easiest explanation: Others BECOME insoluble and INFUSIBLE after the first HEATING and decompose on further increase in TEMPERATURE. These are called thermosetting MATERIALS.

Right option is (a) Thermoplastics

Easiest explanation: Some of them SOFTEN upon heating and regain their original HARDNESS upon subsequent cooling, whereby the heating and cooling cycle can be REPEATED at will. These materials are called thermoplastics.

The correct option is (b) Amorphous

The best explanation: HIGH-polymeric materials show that the MOLECULES in some of them are ARRANGED in a STATE of complete disorder (amorphous state); others EXHIBIT a high degree of order (crystalline and oriented states).

Right choice is (a) Larger

For explanation: The reason that methods conventional for low-molecular-weight compounds prove UNSATISFACTORY for polymers arises from the fact that the polymer MOLECULE is so MUCH larger than the MONOMER.

The correct ANSWER is (c) All of the mentioned

The explanation: The reason that polymers do not possess a sharp melting point is twofold. First of all, the POLYMER is not made up of molecules of identical molecular weight, but contains a mixture of HOMOLOGUES of various degrees of polymerization. Secondly, even if the polymer were of uniform molecular weight, the very size of its large molecules would prevent them from forming the PERFECT sharp melting CRYSTALS which are found in many low molecular weight materials.

Correct answer is (d) All of the mentioned

The EXPLANATION is: The various types of PHYSICAL measurements which can be employed to CHARACTERIZE nonpolymeric molecules, CERTAIN ones are of primary importance. Among these are freezing-point depressions, vapour pressures, boiling POINTS, and crystal structure.