$Cr _{2} O _{7}^{2-}+14 H ^{+}+6 e ^{-} \rightarrow 2 Cr ^{3+}+7 H _{2} O$
The amount of $Cr ^{3+}$ obtained was $0.104\, g$. The
efficiency of the process(in\%) is
(Take : $F =96000\, C$, At. mass of chromium $=52$ )
Using stoichiometry; theoritically
$\frac{ n _{ e ^{\ominus}} used }{6}=$$\frac{ n _{ cr ^{+3}} \text {produced }}{2}$
$\Rightarrow n _{ cr ^{+3}}$ produced $=\frac{2}{6} \times \frac{8 \times 60 \times 2}{96000}$
$=\frac{0.02}{6}$
$\Rightarrow wt _{ cr ^{+3}}$ theoritically produced
$=\left(\frac{0.02}{6} \times 52\right) g$
$\Rightarrow \%$ efficiency $=\frac{0.104 g }{\left(\frac{0.02 \times 52}{6}\right) g } \times 100$
$=60 \%$
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Assertion $(A):$ Gabriel phthalimide synthesis cannot be used to prepare aromatic primary amines.
Reason $(R) :$ Aryl halides do not undergo nucleophilic substitution reaction.
In the light of the above statements, choose the correct answer form the options given below.
$(I) \,C{H_3}CH = C{H_2} + HBr\xrightarrow{{peroxide}}$
$(II)\, C{H_3}CH = C{H_2} + HBr\xrightarrow{{CC{l_4}}}$
$(III)\, C{H_3}C{H_2}C{H_3} + B{r_2}\xrightarrow{{hv}}$
$(IV)\,C{H_3}CH = C{H_2} + B{r_2}\xrightarrow{{CC{l_4}}}$
