Molecular Weight of Polymers

Q. The method of choice of determining the molecular weight of a polymer is:

1. Osmotic pressure
2. Gas density
3. Lowering of freezing point
4. Direct weighing of a single molecule

Q. The method of choice of determining the molecular weight of a polymer is:

1. Osmotic pressure
2. Gas density
3. Lowering of freezing point
4. Direct weighing of a single molecule

Q.

Which of the following colligative property can provide molar mass of proteins ( or polymers or colloids) with greater precision?

1. Relative lowering of vapour pressure

2. Elevation of boiling point

3. Depression of freezing point

4. Osmotic pressure

Q. 65. Find the molality of 90% by volume H2SO4 (specific gravity of H2SO4 solution =1.98 g/ml)

Q. The solution which has lowest freezing point is Options: Should have chosen 1 M CaF2 0.01 M CaSO4 Wrong 0.005 M KI 0.1 M Al2 (SO4)3

Q. In a polymer sample 30% of molecules have a molecularmass of 20, 000, 40% have 30, 000 and the rest 60, 000.what is the weight average molecular mass of the polymer

Q. The number average molecular mass and mass average molecular mass of a polymer are respectively 30, 000 and 40, 000. The poly dispersity index (PDI) of the polymer is

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1. $1$
2. $<1$
3. $0$
4. $>1$

Q. According to the equation,

1. $100$ g
2. $\frac{n}{2}$ g
3. $\frac{100}{n}$ g
4. $100n$ g

Q. A polymeric sample in which $30\%$ molecules have a molecular mass $20,000$, $40\%$ have $30,000$ and the rest $30\%$ have $60,000$. The $\left({\overline{M}}_n\right)$ and $\left({\overline{M}}_w\right)$ of this sample are, respectively:

1. $36,000,43,333$
2. $86,000,72,000$
3. $72,000,86,000$
4. $43,000,36,000$

Q. (i) Write the colligative property which is used to find the molecular mass of macromolecules.
(ii) In non-ideal solution, what type of deviation shows the formation of minimum boiling azeotropes?

Q. The number average molecular mass and mass average molecular mass of a polymer are $30,000$ and $40,000$ respectively. The PDI of the polymer is

1. $<1$
2. $>1$
3. $1$
4. $0$

Q. Percentage strength of 20 volume H2O2 solution is a]3% b]6% c]20% d]15%

Q. Chlorine consists of 75% chlorine-35 and 25% chlorine-37. Calculate the average atomic mass.

1. 35.9
2. 35.5
3. 35.2
4. 36.1

Q. The method preferred for determining the molecular weight of a polymer is___________.

1. osmotic pressure
2. direct weighing of a single molecule
3. gas density
4. lowering of freezing point

Q. $\overline{M_n}$ value is always greater than $\overline{M_w}$ value for synthetic polymers.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. Find out the approximate amount of polythene formed from $20$kg of calcium carbide from the following reactions.

1. $6$g
2. $9$kg
3. $26$kg
4. $29$kg

Q. The solution which has lowest freezing point is Options: Should have chosen 1 M CaF2 0.01 M CaSO4 Wrong 0.005 M KI 0.1 M Al2 (SO4)3

Q. PDI for natural polymers is generally close to:

1. zero
2. $10$
3. $1$
4. $100$

Q. The most suitable property for molecular weight determination of polymers is:

1. osmotic pressure
2. lowering of vapour pressure
3. depression in freezing point
4. elevation in boiling point

Q. If $N_1,N_2,N_3,......$ are the number of molecules with molecular masses $M_1,M_2,M_3,......$ respectively, the mass average molecular mass is expressed as?

1. $\frac{\sum N_i{M_i}^2}{\sum N_i{M}_i}$
2. $\frac{\sum {M_i}^2}{\sum N_i}$
3. $\frac{\sum N_i{M}_i}{\sum M_i}$
4. $\frac{\sum N_i{M}_i}{\sum N_i}$

Q. The most common type of molecular weights used in the case of polymer is :

1. z - average molecular weight method
2. number average molecular weight method
3. all of the above
4. viscosity average molecular weight method

Q. The formation of polyethylene from calcium carbide takes places as follows :
$Ca{C}_2+2H_{2}O\to Ca(OH{)}_2+C_2{H}_2$
$C_2{H}_2+H_2\to C_2{H}_4$
$n{C}_2{H}_4\to (C{H}_2-C{H}_2{)}_n$
The amount of polyethylene obtained from $64$ kg of $Ca{C}_2$ is :

1. $7$ kg
2. $28$ kg
3. $21$ kg
4. $14$ kg

Q. If $N_1,N_2,N_3,....$ are the number of molecules with molecular masses $M_1,M_2,M_3,...$ respectively, then mass average molar mass is expressed as :

1. $\frac{\sum NiM{i}^2}{\sum NiMi}$
2. $\frac{\sum NiMi}{\sum Ni}$
3. $\frac{\sum NiMi}{\sum Mi}$
4. $\frac{\sum M{i}^2}{\sum Ni}$

Q.

Number average molecular mass and weight average molecular mass of synthetic polymers are related as?

1. 
   

2. 
   

3. 
   

4. 
   

Q. The PDI (polydisersity index) is the ratio of weight to number-average molecular masses, $M\overline{w}/M\overline{n}$. In natural polymers, which are generally monodispersed, PDI is ............. and in synthetic polymers which are always polydispersed, PDI is ............. because $M\overline{w}$ is always ............. than $M\overline{n}$. Fill in the blanks.

1. greater than $1$, $1$, higher
2. $1$, greater than $1$, higher
3. less than $1$, $1$, lower
4. $1$, less than $1$, lower

Q. 31. If temperature is increased then solubility increases/decreases?

Q.

of a polymer containing 30% molecules with molecular mass 20, 000, 40% have 30, 000 and the rest have 60, 000 is

1. 36 x 10⁵

2. 36 x 10³

3. 18 x 10³

4. 18 x 10⁵

Q. The formula for calculating $\overline{M_n}$ of a polymer is:

1. $\frac{\sum NiMi}{\sum Ni}$
2. $\frac{\sum NiMi}{\sum Mi}$
3. $\frac{\sum NiM{i}^2}{\sum Mi}$
4. $\frac{\sum NiM{i}^2}{\sum NiMi}$