Q1 · Dec 2019 · 2 marks
In a polymer of N monomer units, the root mean square separation between the two ends is proportional to
- (a) N^{\frac{1}{2}}
- (b) N
- (c) N^{\frac{3}{2}}
- (d) \mathbf{N}^{\mathbf{2}} Root mean square length =\mathrm{N}^{1 / 2} where N is the number of monomer units.
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Answer: (a)
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Q2 · Dec 2019 · 2 marks
The degree of polymerization at \mathbf{t = 1 0 ~ h} of a polymer formed by a stepwise process with polymerization rate constant of 3 \times 10^{-2} \mathbf{M}^{-1} \mathbf{s}^{-1} and an initial monomer concentration of 50 mM is Options:
- (a) 55
- (b) 65
- (c) 550
- (d) 505
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Answer: (a)
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Q3 · June 2017 · 2 marks
For a monodisperse polymer, the number-average molar mass (\bar{M}_N) and weight-average molar mass (\bar{M}_w) are related according to
- (a) \bar{M}_w < \bar{M}_N
- (b) \bar{M}_w = \bar{M}_N
- (c) \bar{M}_w > \bar{M}_N
- (d) \bar{M}_w < \log \bar{M}_N
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Answer: (b)
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Q4 · June 2017 · 2 marks
A polydisperse polymer sample has ten molecules of molar mass 20,000 \mathrm{g\,mol^{-1}} and fifteen molecules of molar mass 10,000 \mathrm{g\,mol^{-1}}. The number-average molar mass (\mathrm{g\,mol^{-1}}) (\bar{M}_n) of the sample is
- (a) 13,000
- (b) 14,000
- (c) 15,000
- (d) 16,000
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Answer: (b)
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Q5 · Dec 2017 · 2 marks
A polymer has the following molar mass distribution The calculated number average molar mass (\bar{M}_n) of the polymer is - (a) 5200
- (b) 5600
- (c) 5800
- (d) 6000
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Answer: (b)
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Q6 · June 2016 · 2 marks
The condensation of hydroxy acid produces a polyster with the probability of linkage at both ends being p. The mole fraction of k-mer chain formation is
- (a) p^k
- (b) p(1-p)^{k-1}
- (c) p^{k-1}(1-p)
- (d) p_{k-1}
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Answer: (d)
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Q7 · June 2015 · 2 marks
The intrinsic viscosity depends on the molar mass as [\eta] = KM_a. The empirical constants K and a are dependent on
- (a) solvent only
- (b) polymer only
- (c) polymer-solvent pair
- (d) polymer-polymer interaction
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Answer: (c)
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Q8 · June 2015 · 2 marks
The stability of a lyophobic colloid is the consequence of
- (a) van der Waals attraction among the solute-solvent adducts
- (b) Brownian motion of the colloidal particles
- (c) insolubility of colloidal particles in solvent
- (d) electrostatic repulsion among double layered colloidal particles
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Answer: (d)
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Q9 · Dec 2015 · 2 marks
The correct form for a simple Langmuir isotherm is
- (a) \theta = K_p
- (b) \theta = (K_p)^{1/2}
- (c) \theta = K_p/(1 + K_p)
- (d) \theta = (1 + K_p)/K_p
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Answer: (c)
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Q10 · Dec 2015 · 2 marks
The correct expression for the product (\bar{M}_n \cdot \bar{M}_w) [\bar{M}_n and \bar{M}_w are the number average and weight average molar masses, respectively, of a polymer] is
- (a) N^{-1}\Sigma_i N_i M_i
- (b) N^{-1}\Sigma_i N_i M_i^{2}
- (c) N/\Sigma_i N_i M_i
- (d) N/\Sigma_i N_i M_i^{2}
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Answer: (b)
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Q11 · Dec 2015 · 2 marks
The average end-to-end distance of a random coil polymer of 10^6 monomers (in units of segment length) is
- (a) 10^{6}
- (b) 10^{5}
- (c) 10^{4}
- (d) 10^{3}
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Answer: (d)
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Q12 · June 2014 · 2 marks
In radical chain polymerization the quantity given by the 'rate of monomer depletion, divided by the rate of propagating radical formation' is called
- (a) kinetic chain length
- (b) propagation efficiency
- (c) propagation rate constant
- (d) polymerization time
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Answer: (a)
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Q13 · June 2012 · 2 marks
During the addition polymerization, the reaction proceeds via
- (a) Step-growth process
- (b) Free-radical chain reaction
- (c) Cascade process
- (d) Addition reaction
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Answer: (b)
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Q14 · June 2012 · 2 marks
The number-average molar mass (\bar{M}_N) and weight-average molar mass (\bar{M}_w) of a polymer are obtained respectively by
- (a) Osmometry and light scattering measurements
- (b) Osmometry and viscosity measurements
- (c) Light scattering and sedimentation measurements
- (d) Viscosity and light scattering measurements
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Answer: (b)
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Q15 · June 2011 · 2 marks
There are several types of mean molar masses for polymer and they are dependent on experimental methods like: (1) Osmometry (2) Light scattering (3) Sedimentation. Correct relation between mean molar masses and experimental method is:
- (a) \overline{M}_n \Rightarrow (3), \overline{M}_w \Rightarrow (2), \overline{M}_z \Rightarrow (1)
- (b) \overline{M}_n \Rightarrow (2), \overline{M}_w \Rightarrow (3), \overline{M}_z \Rightarrow (1)
- (c) \overline{M}_n \Rightarrow (1), \overline{M}_w \Rightarrow (2), \overline{M}_z \Rightarrow (3)
- (d) \overline{M}_n \Rightarrow (1), \overline{M}_w \Rightarrow (3), \overline{M}_z \Rightarrow (2)
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Answer: (c)
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