Physical Chemistry Questions

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is ${\text{CH}}_3\text{OH}(l)+\frac{3}{2}{\text{O}}_2(g)\to {\text{CO}}_2(g)+2{\text{H}}_2\text{O}(l)$. At $298\text{K}$ standard Gibb’s energies of formation for ${\text{CH}}_3\text{OH}(l)$, ${\text{H}}_2\text{O}(l)$ and ${\text{CO}}_2(g)$ are $-166.2$, $-237.2$ and $-394.4{\text{kJ mol}}^{-1}$ respectively. If standard enthalpy of combustion of methanol is $-726{\text{kJ mol}}^{-1}$, efficiency of the fuel cell will be:

A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

Which of the following statements is incorrect regarding physisorption?

Two liquids $X$ and $Y$ form an ideal solution. At $300\text{K}$, vapour pressure of the solution containing $1\text{mol}$ of $X$ and $3\text{mol}$ of $Y$ is $550\text{mm Hg}$. At the same temperature, if $1\text{mol}$ of $Y$ is further added to this solution, vapour pressure of the solution increases by $10\text{mm Hg}$. Vapour pressure (in $\text{mm Hg}$) of $X$ and $Y$ in their pure states will be, respectively:

Given: $E_{{\text{Fe}}^{3+}/\text{Fe}}^{\circ }=-0.036\text{V}$, $E_{{\text{Fe}}^{2+}/\text{Fe}}^{\circ }=-0.439\text{V}$. The value of standard electrode potential for the change, ${\text{Fe}}^{3+}(aq)+e^{-}\to {\text{Fe}}^{2+}(aq)$ will be:

On the basis of the following thermochemical data: ($\Delta H_f^{\circ }{\text{H}}^{+}(aq)=0$)${\text{H}}_2\text{O}(l)\to {\text{H}}^{+}(aq)+{\text{OH}}^{-}(aq)$; $\Delta H=57.32\text{kJ}$${\text{H}}_2(g)+\frac{1}{2}{\text{O}}_2(g)\to {\text{H}}_2\text{O}(l)$; $\Delta H=-286.20\text{kJ}$ The value of enthalpy of formation of ${\text{OH}}^{-}$ ion at $25^{\circ }\text{C}$ is:

The half life period of a first order chemical reaction is $6.93\text{minutes}$. The time required for the completion of $99\%$ of the chemical reaction will be ($\log 2=0.301$):

Solid $\text{Ba}({\text{NO}}_3{)}_2$ is gradually dissolved in a $1.0\times 10^{-4}\text{M}$ ${\text{Na}}_2{\text{CO}}_3$ solution. At what concentration of ${\text{Ba}}^{2+}$ will a precipitate begin to form? ($K_{sp}$ for ${\text{BaCO}}_3=5.1\times 10^{-9}$).

Copper crystallizes in fcc with a unit cell length of $361\text{pm}$. What is the radius of copper atom?