If a polythene sample contains two monodisperse fractions in the ratio 2 : 3 with degree of polymerization 100 and 200, respectively, then its weight average molecular weight will be :
Show Hint
- 4900
- 4600
- 4300
- 5200
The Correct Option is A
Solution and Explanation
\(M_1 = 100\times 28 = 2800\) and \(M_2 = 200\times 28 = 5600\).
The fractions are in the ratio \(N_1:N_2 = 2:3\) (by number of molecules).
\(\overline{M_w} = \dfrac{N_1M_1^2 + N_2M_2^2}{N_1M_1 + N_2M_2} = \dfrac{2(2800)^2 + 3(5600)^2}{2(2800)+3(5600)}\)
Numerator \(= 2(7.84\times10^6) + 3(31.36\times10^6) = 109.76\times10^6\)
Denominator \(= 5600 + 16800 = 22400\)
\(\overline{M_w} = 109.76\times10^6 / 22400 = 4900\)
Answer: (1) 4900
Top JEE Main Chemistry Questions
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)- At equilibrium the concentrations of and in a sealed vessel at . What will be for the reaction
- Find out the major products from the following reactions
Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
- The correct order of atomic radii is:
Top JEE Main molecular mass of polymers Questions
- A compound \((x)\) with molar mass \(108\) \(g\) \(mol^{-1}\) undergoes acetylation to give product with molar mass \(192\) \(g\) \(mol^{-1}\)
- Haemoglobin contains \(0.34\%\) of iron by mass. The number of Fe atoms in \(3.3\) g of haemoglobin is(Given: Atomic mass of Fe is \(56\) u, \(N_A\) = \(6.022 × 1023\) \(mol^{–1}\))
Top JEE Main Questions
- Two masses $m$ and $\frac{m}{2}$ are connected at the two ends of a massless rigid rod of length $l$. The rod is suspended by a thin wire of torsional constant $k$ at the centre of mass of the rod-mass system(see figure). Because of torsional constant $k$, the restoring torque is $\tau =k\theta$ for angular displacement $\theta$. If the rod is rota ted by $\theta_0$ and released, the tension in it when it passes through its mean position will be:
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)- The value of is
- The number of terms of an is even. The sum of the odd terms is and of the even terms is . The last term exceeds the first by . Then the number of terms in the series is ______.
A black body is at a temperature of 2880 K. The energy of radiation emitted by this body with wavelength between 499 nm and 500 nm is U1, between 999 nm and 1000 nm is U2 and between 1499 nm and 1500 nm is U3. The Wien's constant, b = 2.88×106 nm-K. Then,