Which of the following is NOT TRUE about nucleophilic addition reactions of aldehydes?
2,4 DNP derivatives are useful to identify aldehydes and ketones
Hemiacetals are gem-dialkoxy compounds
The hydrogensulphite addition product is useful for separation and purification of aldehydes
Aldehydes and ketones react very slowly with pure HCN to yield cyanohydrins
$$ \text { The solution of } \boldsymbol{d} \boldsymbol{y}=\boldsymbol{\operatorname { c o s }} \boldsymbol{x}(\mathbf{2}-\boldsymbol{y} \boldsymbol{\operatorname { c o s e c }} \boldsymbol{x}) \boldsymbol{d} \boldsymbol{x} \quad \text { where } y=\sqrt{2} \text { when } x=\frac{\boldsymbol{\pi}}{4} \text { is } $$
$y=\sin x+\frac{1}{2} \operatorname{cosec} x$
$y=\tan \left(\frac{x}{2}\right)+\cot \left(\frac{x}{2}\right)$
$y \sin x=\frac{1}{2} \cos 2 x$
$y=\frac{1}{\sqrt{2}} \sec x+\sqrt{2} \cos \left(\frac{x}{2}\right)$
$$ \text { The conjugate of } z=\frac{(\mathbf{4}+\boldsymbol{i})(\mathbf{1}-\boldsymbol{i})}{(\mathbf{1}+\boldsymbol{i})(\mathbf{2}-\boldsymbol{i})} $$
$\frac{6}{5}+\frac{7}{5} i$
$\frac{1}{2}-\frac{1}{2} i$
$\frac{6}{5}-\frac{7}{5} i$
$\frac{1}{2}+\frac{1}{2} i$
If A and B are two square matrices of the same order such that $\mathrm{AB}=\mathrm{A}$ and $\mathrm{BA}=\mathrm{B}$, then $(\boldsymbol{A}+\boldsymbol{B})^2$ is equal to:
$A^2+B^2+2 A$
$A+B$
$A^2+B^2$
$2(A+B)$
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