The hydrogen electrode is dipped in a solution of $\mathrm{pH}=3$ at $25^{\circ} \mathrm{C}$. The potential of the electrode will be _________ $\times 10^{-2} \mathrm{~V}$.

$\left(\frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.059 \mathrm{~V}\right)$

A mixture of hydrogen and oxygen contains $40 \%$ hydrogen by mass when the pressure is $2.2$ bar. The partial pressure of hydrogen is bar. (Nearest Integer)

The standard reduction potentials at $298 \mathrm{~K}$ for the following half cells are given below :

$\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \quad \mathrm{E}^{\circ}=1.33 \mathrm{~V}$

The first overtone frequency of an open organ pipe is equal to the fundamental frequency of a closed organ pipe. If the length of the closed organ pipe is 20 cm. The length of the open organ pipe is _____________ cm.

Among the following ores Bauxite, Siderite, Cuprite, Calamine, Haematite, Kaolinite, Malachite, Magnetite, Sphalerite, Limonite, Cryolite, the number of principal ores if iron is _____________.

The solubility product of $\mathrm{BaSO}_{4}$ is $1 \times 10^{-10}$ at . The solubility of in solution is ___________ (nearest integer).

The solubility product of a sparingly soluble salt A₂X₃ is 1.1 $\times$ 10^$-$23. If specific conductance of the solution is 3 $\times$ 10 S m S m mol. The value of x is ___________.

The $\mathrm{pH}$ of an aqueous solution containing $1 \mathrm{M}$ benzoic acid $\left(\mathrm{pK}_{\mathrm{a}}=4.20\right)$ and sodium benzoate is 4.5. The volume of benzoic acid solution in of this buffer solution is _________ . (given : )

An analyst wants to convert $1 \mathrm{~L} \mathrm{~HCl}$ of $\mathrm{pH}=1$ to a solution of of . The volume of water needed to do this dilution is __________ . (Nearest integer)

$\mathrm{K}_{\mathrm{a}}$ for butyric acid $\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOH}\right)$ is . The of solution of butyric acid is __________ . (Nearest integer)

$\text{FeO}_4^{2-} \xrightarrow{+2.2\text{V}} \text{Fe}^{3+} \xrightarrow{+0.70\text{V}} \text{Fe}^{2+} \xrightarrow{-0.45\text{V}} \text{Fe}^0$

The dissociation constant of acetic acid is $x\times10^{-5}$. When 25 mL of 0.2 $\mathrm{M~CH_3COONa}$ solution is mixed with 25 mL of 0.02 solution, the pH of the resultant solution is found to be equal to 5. The value of is ____________

$600 \mathrm{~mL}$ of $0.01~\mathrm{M} ~\mathrm{HCl}$ is mixed with $400 \mathrm{~mL}$ of . The of the mixture is ___________ . (Nearest integer)