Class 12th

The theory that can completely/properly explain the nature of bonding in $\left[\mathrm{N}\mathrm{i}(\mathrm{C}\mathrm{O}{)}_4\right]$ $\left[{}_{}\right]$ is

The purest form of commercial iron is

For the reaction

$2{\mathrm{H}}_2\left(\mathrm{g}\right)+2\mathrm{N}\mathrm{O}\left(\mathrm{g}\right)?{\mathrm{N}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}$ , the observed rate expression is, rate = ${\mathrm{k}}_{\mathrm{f}}[\mathrm{N}\mathrm{O}{]}^2\left[{\mathrm{H}}_2\right]$ . The rate expression for the reverse reaction is:

Three charged particles $A,B$ $$ and $C$ $$ with charges $-4q,2q$ $$ and $$ $-2q$  are present on the circumference of a circle of radius $d$ $$ . The charged particles $A,C$ $$ and centre $O$ $$ of the circle formed an equilateral triangle as shown in figure. Electric field at $\mathrm{O}$ $$ along $\mathrm{x}$ $$ -direction is:

The atomic radius of $\mathrm{A}\mathrm{g}$ $$ is closest to

At ${}^{}$ ${35}^{?}\mathrm{C}$ , the vapour pressure of ${\mathrm{C}\mathrm{S}}_2$ ${}_{}$ is $$ $512\mathrm{m}\mathrm{m}$ of $\mathrm{H}\mathrm{g}$ $$ and that of acetone is $344\mathrm{m}\mathrm{m}$ $$ of $\mathrm{H}\mathrm{g}$ $$ . A solution of ${\mathrm{C}\mathrm{S}}_2$ ${}_{}$ in acetone has a total vapour pressure of $600\mathrm{m}\mathrm{m}$ $$ of $\mathrm{H}\mathrm{g}$ $$ . The false statement among the following is

The refining method used when the metal and the impurities have low and high melting temperatures, respectively is

Effective capacitance of parallel combination of two capacitors $C_1$ ${}_{}$ and ${}_{}$ $C_2$ is $10\mu \mathrm{F}$ $$ . When these capacitor are individually connected to a voltage source $1\mathrm{V}$ of $1\mathrm{V}$ $$ , the energy stored in the capacitor $C_2$ ${}_{}$ is 4 times that of ${}_{}$ $C_1$ . If these capacitors are connected in series, their effective capacitance will be

In the following reactions, products(A) and $\left(B\right)$ respectively are $\underset{\text{(Hot and Conc)}}{\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}}+{\mathrm{C}\mathrm{l}}_2?\left(\mathrm{A}\right)+$ side products $\mathrm{C}\mathrm{a}(\mathrm{O}\mathrm{H}{)}_2{\mathrm{C}\mathrm{l}}_2?(\mathrm{B})+$ side products (Dry)

The balancing length for a cell is $560\mathrm{c}\mathrm{m}$ in a potentiometer experiment. When an external resistance of $10\mathrm{\Omega }$ is connected in parallel to the cell, the balancing length changes by $60\mathrm{c}\mathrm{m}$ . If the internal resistance of the cell is $\frac{N}{10}\mathrm{\Omega }$ , where $N$ is an integer then value of $N$  is