Physical Chemistry PYQ — Page 50

The de Broglie wavelength of an electron in the ${4}^{th}$ Bohr orbit is:

The number of molecules with energy greater than the threshold energy for a reaction increases five fold by a rise of temperature from ${27}^{o}C$ to ${42}^{o}C$. Its energy of activation in $J/\mathrm{mol}$ is _________ (Take $\mathrm{ln}5=1.6094;R=8.314J{\mathrm{mol}}^{-1}$)

Consider the hypothetical situation where the azimuthal quantum number, $l$, takes values $0,1,2,\ldots \ldots ..n+1$. Where n is the principal quantum number. Then, the element with atomic number:

The rate of a reaction decreased by $3.555$ times when the temperature was changed from $40^{\circ}C\mathrm{to}30^{\circ}C$. the activation energy (in $\mathrm{kJ}{\mathrm{mol}}^{-1}$) of the reaction is ________ .

The compound that cannot act both as oxidizing and reducing agent is

The mole fraction of glucose $({C}_{6}{H}_{12}{O}_{6})$ in an aqueous binary solution is $0.1.$ The mass percentage of water in it, to the nearest integer, is $\ldots \ldots \ldots$

The osmotic pressure of a solution of $\mathrm{NaCl}$ is $0.10$ atm and that of a glucose solution is $0.20$ atm. The osmotic pressure of a solution formed by mixing $1L$ of the sodium chloride solution with $2L$ of the glucose solution is $x\times {10}^{-3}$ atm. $x$ is ________ (nearest integer)

During the nuclear explosion, one of the products is ${}^{90}Sr$ with half life of $6.93$ years. If $1\mu g$ of ${}^{90}Sr$ was absorbed in the bones of a newly born baby in place of $Ca,$ how much time, in years, is required to reduce it by $90%$ if it is not lost metabolically ____________.

How much amount of $NaCl$ should be added to $600g$ of water $(\rho =1.00g/mL)$ to decrease the freezing point of water to $-0.2{}^{o}C$? ________. (The freezing point depression constant for water $=2 K kg{mol}^{-1}$ )

For the following Assertion and Reason, the correct option is Assertion (A) : When $\mathrm{Cu}$ (II) and sulphide ions are mixed, they react together extremely quickly to give a solid. Reason (R) : The equilibrium constant of ${\mathrm{Cu}}^{2+}(\mathrm{aq})+{S}^{2-}(\mathrm{aq})\rightleftharpoons \mathrm{Cus}(s)$ is high because the solubility product is low.

Five moles of an ideal gas at $1$ bar and $298K$ is expanded into vacuum to double the volume. The work done is :

Henry's constant (in kbar) for four gases $\alpha ,\beta ,\gamma$ and $\delta$ in water at $298K$ is given below : $\begin{matrix} & \alpha & \beta & \gamma & \delta \\ {K}_{H} & 50 & 2 & 2\times {10}^{-5} & 0.5\end{matrix}$ (density of water $={10}^{3}k{\mathrm{gm}}^{-3}$ at $298K$ ) This table implies that :

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve $10ppm$ of iron in $100kg$ of wheat is ____________. Atomic weight: $Fe=55.85;S=32.00;O=16.00$

The heat of combustion of ethanol into carbon dioxides and water is $-327$ Kcal at constant pressure. The heat evolved (in cal) at constant volume at $27^{\circ}C$ (if all gases behave ideally) is $(R=2{\mathrm{calmol}}^{-1}{K}^{-1})$________

$0.023\times {10}^{22}$ molecules are present in $10g$of a substance $x''.$ The molarity of a solution containing $5g$ of substance 'x' in 2 L solution is $_________\times {10}^{-3}$

For the reaction $2A+3B+\frac{3}{2}C\rightarrow 3P$, which statement is correct?

For the disproportionation reaction $2{\mathrm{Cu}}^{+}(\mathrm{aq})\rightleftharpoons \mathrm{Cu}(s)+{\mathrm{Cu}}^{2+}(\mathrm{aq})$ at $298K,$$\mathrm{ln}K$ (where $K$ is the equilibrium constant) is _______$\times {10}^{-1}$ Given $:(E{^{\circ}}_{{\mathrm{Cu}}^{2+}/{\mathrm{Cu}}^{+}}=0.16VE{^{\circ}}_{{\mathrm{Cu}}^{+}/\mathrm{Cu}}=0.52V\frac{\mathrm{RT}}{F}=0.025)$

For the given cell; $\mathrm{Cu}(s)|{\mathrm{Cu}}^{2+}({C}_{1}M)||{\mathrm{Cu}}^{2+}({C}_{2}M)|\mathrm{Cu}(s)$ change in Gibbs energy $(\Delta G)$ is negative, it :

The variation of molar conductively with concentration of an electrolyte (X) in aqueous solution is shown in the given figure.  The electrolyte X is :

The redox reaction among the following is

The shortest wavelength of $H$ atom in the Lyman series is ${\lambda }_{1}$. The longest wavelength in the Balmer series of ${\mathrm{He}}^{+}$ is :

The oxidation states of transition metal atoms in ${K}_{2}{\mathrm{Cr}}_{2}{O}_{7},{\mathrm{KMnO}}_{4}$ and ${K}_{2}{\mathrm{FeO}}_{4},$ respectively, are $x,y$ and $z$ . The sum of $x,y$ and $z$ is______

An oxidation-reduction reaction in which 3 electrons are transferred has a ${\Delta G}^{0}$ of $17.37\mathrm{kJ}{\mathrm{mol}}^{-1}$ at $25^{\circ}C.$ The value of ${E}_{\mathrm{cell}}^{o}$ (in V) is $_______\times {10}^{-2}$. $(1F=96500C{\mathrm{mol}}^{-1})$

Two solutions, $A$ and $B,$ each of $100L$ was made by dissolving $4g$ of $NaOH$ and $9.8g$ of ${H}_{2}S{O}_{4}$ in water, respectively. The $pH$ of the resultant solution obtained from mixing $40L$ of solution $A$ and $10L$ of solution $B$ is ____________. $(\mathrm{log}2=0.3)$