Which of the following minerals is not remobilized in plants?

Among the bromides $(I)-(III)$ given below,the order of reactivity in $S_N1$ reaction is:

$A$ reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by $62^{\circ} C$,the efficiency of the engine is doubled. The temperatures of the source and sink are

In the circuit shown, if a conducting wire is connected between points $A$ and $B$, the current in this wire will

Let $\overrightarrow{a}=\hat{i}-2 \hat{j}+3 \hat{k}$,$\overrightarrow{b}=2 \hat{i}+3 \hat{j}-\hat{k}$ and $\overrightarrow{c}=\lambda \hat{i}+\hat{j}+(2 \lambda-1) \hat{k}$. If $\overrightarrow{c}$ is parallel to the plane containing $\overrightarrow{a}$ and $\overrightarrow{b}$,then $\lambda$ is equal to

In the brown ring complex $[Fe(H_2O)_5NO]SO_4$,the primary valency (oxidation state) of $Fe$ is: