Download App

Polymers — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryPolymers1 Mark
MCQ
What is not true regarding free radical polymerisation of propene?
  • A
    Without proper control, atactic polypropylene is formed.
  • B
    Use of Ziegler$-$Natta catalyst results in isotactic polypropylene.
  • ✓
    During polymerisation, a linear unbranched, crystalline polymer is usually obtained.
  • D
    During polymerisation, a secondary free radical is produced in every step.
✓

Answer

Correct option: C.
During polymerisation, a linear unbranched, crystalline polymer is usually obtained.
The statement $(C)$ is not true. During polymerization, a branched polymer is usually obtained. Chain branching always occur during olefenic polymerization due to abstraction of some $H-$radical from the growing polymer chain.
Note$:\ 1^\circ $ free radical forms $2^\circ $ free radical by abstracting hydrogen at middle of another chain, which further adds to propene and there is growing of the branch. Ziegler Natta catalyst is titanium chloride and triethyl aluminum $\left[\mathrm{TiCl}_4+\mathrm{Al}\left(\mathrm{C}_2 \mathrm{H}_5\right)_3\right]$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from Polymers→Polymers — all question types→Chemistry STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Assertion: Phenyl is used as a household germicide.
Reason : Phenyl is phenol derivative and phenol is an effective germicide
→
Charge required to liberate  $11.5\,g $ sodium is
→
The product $(C)$ in thbelow mentioned reaction is:

${CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{Br} \xrightarrow[\Delta]{\mathrm{KOH}_{(a k)}} \mathrm{A} \xrightarrow{\mathrm{HBr}} \mathrm{B} \xrightarrow[\mathrm{KOH}_{(a) i}]{\Delta} \mathrm{C}$

→
Polyphosphates are used as softening agents since
→
Identify correct statements from below:

$A$. The chromate ion is square planar.

$B$. Dichromates are generally prepared from chromates.

$C$. The green manganate ion is diamagnetic.

$D$. Dark green coloured $\mathrm{K}_2 \mathrm{MnO}_4$ disproportionates in a neutral or acidic medium to give permanganate.

$E$. With increasing oxidation number of transition metal, ionic character of the oxides decreases.

Choose the correct answer from the options given below:

→
Two $5$ molal solutions are prepared by dissolving a non-electrolyte, non-volatile solute separately in the solvents $X$ and $Y$. The molecular weights of the solvents are $M_X$ and $M_Y$, respectively where $M_X\, = \frac{3}{4} M_Y$. The relative lowering of  vapour pressure of the solution in $X$ is $''m''$ times that of the solution in $Y$. Given that the number of moles of solute is very small in comparison to that of solvent, the value of $''m''$  is
→
Seliwanoff test and Xanthoproteic test are used for the identification of $....$ and $....$ respectively
→
The position of $–Br$ in the compound in $\mathrm{CH}_3 \mathrm{CH}=\mathrm{CHC}(\mathrm{Br})\left(\mathrm{CH}_3\right)_2$ can be classified as $........$
→
$RCOCl + 2M{e_2}NH \to A + M{e_2}\mathop {N{H_2}C{l^ - }}\limits^{ + \,\,\,\,\,\,\,\,\,\,\,\,\,\,} $ Here $A$ is
→
Chemically, detergent is:
→