Physical Chemistry PYQ — Page 17

Fuel cell, using hydrogen and oxygen as fuels, A. has been used in spaceship B. has as efficiency of \(40 \%\) to produce electricity C. uses aluminum as catalysts D. is eco-friendry E. is actually a type of Galvanic cell only Choose the correct answer from the options given below:

At \(-20^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\) pressure, a cylinder is filled with equal number of \(\mathrm{H}_2, \mathrm{I}_2\) and \(\mathrm{HI}\) molecules for the reaction \(\mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{g})\), the \(\mathrm{K}_{\mathrm{p}}\) for the process is \(x \times 10^{-1}\). \(\mathrm{x}=\) _____ [Given : \(\mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\)]

One of the commonly used electrode is calomel electrode. Under which of the following categories, calomel electrode comes?

What is the standard EMF of the cell?

What is the EMF of the cell under the given conditions using the Nernst equation?

The emf of cell Tl \(\left|\underset{(0.001 \mathrm{M})}{\mathrm{Tl}^{+}}\right|\left|\underset{(0.01 \mathrm{M})}{\mathrm{Cu}^{2+}}\right| \mathrm{Cu}\) is \(0.83 \mathrm{~V}\) at \(298 \mathrm{~K}\). It could be increased by :

The standard reduction potentials at \(298 \mathrm{~K}\) for the following half cells are given below : \(\begin{array}{ll} \mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \mathrm{E}^{\circ}=1.33 \mathrm{~V} \\ \mathrm{Fe}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \qquad \mathrm{E}^{\circ}=-0.04 \mathrm{~V} \\ \mathrm{Ni}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{Ni} \qquad \mathrm{E}^{\circ}=-0.25 \mathrm{~V} \\ \mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Ag} \quad\qquad \mathrm{E}^{\circ}=0.80 \mathrm{~V} \\ \mathrm{Au}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Au} \qquad \mathrm{E}^{\circ}=1.40 \mathrm{~V} \end{array}\) Consider the given electrochemical reactions, The number of metal(s) which will be oxidized be \(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\), in aqueous solution is ______

Compare the energies of following sets of quantum numbers for multielectron system. (A) \(\mathrm{n}=4,1=1\) (B) \(\mathrm{n}=4, \mathrm{l}=2\) (C) \(\mathrm{n}=3,1=1\) (D) \(\mathrm{n}=3,1=2\) (E) \(\mathrm{n}=4,1=0\) Choose the correct answer from the options given below :

For the given reaction, choose the correct expression of ${K}_{C}$ from the following: ${{\mathrm{Fe}}^{3+}}_{(\mathrm{aq})}+{{\mathrm{SCN}}^{-}}_{(\mathrm{aq})}\rightleftharpoons (\mathrm{FeSCN}{{)}^{2+}}_{(\mathrm{aq})}$

For a sparingly soluble salt \(\mathrm{AB}_2\), the equilibrium concentrations of \(\mathrm{A}^{2+}\) ions and \(B^{-}\)ions are \(1.2 \times 10^{-4} \mathrm{M}\) and \(0.24 \times 10^{-3} \mathrm{M}\), respectively. The solubility product of \(\mathrm{AB}_2\) is :

$2{\mathrm{MnO}}_{4}^{-}+{\mathrm{bI}}^{-}+{\mathrm{cH}}_{2}O\rightarrow {\mathrm{xI}}_{2}+{\mathrm{yMnO}}_{2}+{\mathrm{zOH}}^{-}$ If the above equation is balanced with integer coefficients, the value of $z$ is ________.

\(\Delta_{\text {vap }} \mathrm{H}^{\ominus}\) for water is \(+40.79 \mathrm{~kJ} \mathrm{~mol}^{-1}\) at 1 bar and \(100{ }^{\circ} \mathrm{C}\). Change in internal energy for this vapourisation under same condition is \(\qquad\) \(\mathrm{kJ} \mathrm{mol}^{-1}\). (Integer answer) (Given \(\mathrm{R}=8.3 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\))

Molarity \((\mathrm{M})\) of an aqueous solution containing \(x \mathrm{~g}\) of anhyd. \(\mathrm{CuSO}_4\) in \(500 \mathrm{~mL}\) solution at \(32{ }^{\circ} \mathrm{C}\) is \(2 \times 10^{-1} \mathrm{M}\). Its molality will be ______ \(\times 10^{-3} \mathrm{~m}\). (nearest integer). [Given density of the solution \(=1.25 \mathrm{~g} / \mathrm{mL}\)]

Total number of species from the following which can undergo disproportionation reaction ___________. ${H}_{2}{O}_{2},{\mathrm{ClO}}_{3}^{-},{P}_{4},{\mathrm{Cl}}_{2},\mathrm{Ag},{\mathrm{Cu}}^{+1},{F}_{2},{\mathrm{NO}}_{2},{K}^{+}$

For the electro chemical cell \(\begin{gathered} \text { If } \mathrm{E}_{\left(\mathrm{M}^{2+} / \mathrm{M}\right)}^0=0.46 \mathrm{~V} \text { and } \mathrm{E}_{\left(\mathrm{x} / \mathrm{X}^{2-}\right)}^0=0.34 \mathrm{~V} \text {. } \end{gathered}\) Which of the following is correct?

$0.05\mathrm{cm}$ thick coating of silver is deposited on a plate of $0.05{m}^{2}$ area. The number of silver atoms deposited on plate are _______$\times {10}^{23}$. (At mass Ag $=108,d=7.9g{\mathrm{cm}}^{-3})$ Round off to the nearest integer.

Combustion of 1 mole of benzene is expressed at \(\mathrm{C}_6 \mathrm{H}_6(\mathrm{l})+\frac{15}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow 6 \mathrm{CO}_2(\mathrm{~g})+3 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \text {. }\) The standard enthalpy of combustion of \(2 \mathrm{~mol}\) of benzene is \(-^{\prime} x^{\prime} \mathrm{kJ}\). \(x=\) ______ Given: 1. standard Enthalpy of formation of \(1 \mathrm{~mol}\) of \(\mathrm{C}_6 \mathrm{H}_6(\mathrm{l})\), for the reaction \(6 \mathrm{C}\) (graphite) \(+3 \mathrm{H}_2(\mathrm{~g}) \rightarrow \mathrm{C}_6 \mathrm{H}_6(\mathrm{l})\) is \(48.5 \mathrm{~kJ} \mathrm{~mol}^{-1}\). 2. Standard Enthalpy of formation of \(1 \mathrm{~mol}\) of \(\mathrm{CO}_2(\mathrm{~g})\), for the reaction \(\mathrm{C}\) (graphite) \(+\mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{CO}_2(\mathrm{~g})\) is \(-393.5 \mathrm{~kJ} \mathrm{~mol}^{-1}\). 3. Standard and Enthalpy of formation of \(1 \mathrm{~mol}\) of \(\mathrm{H}_2 \mathrm{O}(\mathrm{l})\), for the reaction \(\mathrm{H}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{l})\) is \(-286 \mathrm{~kJ} \mathrm{~mol}^{-1}\).

Molality ( \(\mathrm{m}\) ) of \(3 \mathrm{M}\) aqueous solution of \(\mathrm{NaCl}\) is : (Given : Density of solution \(=1.25 \mathrm{~g} \mathrm{~mL}^{-1}\), Molar mass in \(\mathrm{g} \mathrm{mol}^{-1}: \mathrm{Na}-23, \mathrm{Cl}-35.5\))

Combustion of glucose \(\left(\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6\right)\) produces \(\mathrm{CO}_2\) and water. The amount of oxygen (in g) required for the complete combustion of \(900 \mathrm{~g}\) of glucose is : [Molar mass of glucose in \(\mathrm{g} \mathrm{mol}^{-1}=180\) ]

Number of moles of methane required to produce $22g{\mathrm{CO}}_{2(g)}$ after combustion is $x\times {10}^{–2}$ moles. The value of $x$ is

For a certain reaction at $300K,K=10,$ then $\Delta G^{\circ}$ for the same reaction is – ________ $\times {10}^{-1}\mathrm{kJ}{\mathrm{mol}}^{-1}.$ (Given $R=8.314{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$)

The electronic configuration of Einsteinium is : (Given atomic number of Einsteinium \(=99)\)

Frequency of the de-Broglie wave of electron in Bohr's first orbit of hydrogen atom is _______ \(\times 10^{13} \mathrm{~Hz}\) (nearest integer). \(\begin{aligned} & \text { [Given : } \mathrm{R}_{\mathrm{H}}(\text { Rydberg constant })=2.18 \times 10^{-18} \mathrm{~J}, h \text { (Plank's } \\ & \text { constant })=6.6 \times 10^{-34} \mathrm{~J} \text {.s.] } \end{aligned}\)

The de-Broglie's wavelength of an electron in the \(4^{\text {th }}\) orbit is \(\qquad\) \(\pi \mathrm{a}_0 \cdot\left(\mathrm{a}_0=\right.\) Bohr's radius \()\)