21. $\mathrm { NiCl } _ { 2 } \left\{ \mathrm { P } \left( \mathrm { C } _ { 2 } \mathrm { H } _ { 5 } \right) _ { 2 } \left( \mathrm { C } _ { 6 } \mathrm { H } _ { 5 } \right) \right\} _ { 2 }$ exhibits temperature dependent magnetic behaviour (paramagnetic/ diamagnetic). The coordination geometries of $\mathrm { Ni } ^ { 2 + }$ in the paramagnetic and diamagnetic states are respectively\\
(A) tetrahedral and tetrahedral\\
(B) square planar and square planar\\
(C) tetrahedral and square planar\\
(D) square planar and tetrahedral

\section*{ANSWER : C}
\begin{enumerate}
  \setcounter{enumi}{21}
  \item In the cyanide extraction process of silver from argentite ore, the oxidizing and reducing agents used are\\
(A) $\mathrm { O } _ { 2 }$ and CO respectively.\\
(B) $\mathrm { O } _ { 2 }$ and Zn dust respectively.\\
(C) $\mathrm { HNO } _ { 3 }$ and Zn dust respectively.\\
(D) $\mathrm { HNO } _ { 3 }$ and CO respectively.
\end{enumerate}

\section*{ANSWER : B}
\begin{enumerate}
  \setcounter{enumi}{22}
  \item The reaction of white phosphorus with aqueous NaOH gives phosphine along with another phosphorus containing compound. The reaction type; the oxidation states of phosphorus in phosphine and the other product are respectively\\
(A) redox reaction; - 3 and - 5\\
(B) redox reaction; + 3 and + 5\\
(C) disproportionation reaction; - 3 and + 5\\
(D) disproportionation reaction; - 3 and + 3
\end{enumerate}

Zero Marks to all\\