The molar conductivity of \( 0.007 \,M \) acetic acid is \( 20\, S\, cm ^{2} mol ^{-1} \) . What is the dissociation constant of acetic acid? Choose the correct option. \( \left[\Lambda_{ H ^{+}}^{\circ}=350 \,S \,cm ^{2} mol ^{-1}, \Lambda_{ CH _{3} COO ^{-}}^{\circ}=50\, S\, cm ^{2} mol ^{-1}\right] \)
(A) \( 1.75 \times 10^{-4}\, mol\, L ^{-1} \)
(B) \( 2.50 \times 10^{-4}\, mol\, L ^{-1} \)
(C) \( 1.75 \times 10^{-5}\, mol\, L ^{-1} \)
(D) \( 2.50 \times 10^{-5} \, mol\, L ^{-1} \)

Choose the correct option for the total pressure (in atm.) in a mixture of \( 4 \,g\, O _{2} \) and \( 2 \,g \,H _{2} \) confined in a total volume of one litre at \( 0^{\circ} C \) is : \( \left[\right. \) Given \( \left.R = 0.082 \,L \,atm\, mol ^{-1} K ^{-1}, T =273\, K \right] \)
(A) \( 2.518 \)
(B) \( 2.602 \)
(C) \( 25.18 \)
(D) \( 26.02 \)

The correct option for the value of vapour pressure of a solution at \( 45^{\circ} C \) with benzene to octane in molar ratio \( 3: 2 \) is : [At \( 45^{\circ} C \) vapour pressure of benzene is \( 280\, mm\, Hg \) and that of octane is \( 420\, mm \,Hg \) . Assume Ideal gas]

(A) 160 mm of Hg
(B) 168 mm of Hg
(C) 336 mm of Hg
(D) 350 mm of Hg

For irreversible expansion of an ideal gas under isothermal condition, the correct option is:
(A) \( \Delta U =0, \Delta S _{\text {total }}=0 \)
(B) \( \Delta U \neq 0, \Delta S _{\text {total }} \neq 0 \)
(C) \( \Delta U =0, \Delta S _{\text {total }} \neq 0 \)
(D) \( \Delta U \neq 0, \Delta S _{\text {total }}=0 \)

Which of the following molecules is non-polar in nature?
(A) \( POCl _{3} \)
(B) \( CH _{2} O \)
(C) \( SbCl _{5} \)
(D) \( NO _{2} \)

In which one of the following arrangements the given sequence is not strictly according to the properties indicated against it?
(A) \( HF < HCl < HBr < HI \) : Increasing acidic strength

(B) \( H _{2} O < H _{2} S < H _{2} Se < H _{2} Te \) : Increasing \( pK_{a} \) values
(C) \( NH _{3}< PH _{3} < AsH _{3}< SbH _{3} \) : Increasing acidic character
(D) \( CO _{2}< SiO _{2} < SnO _{2}< PbO _{2} \) : Increasing oxidizing power

The slope of Arrhenius Plot \( \left(\ln k\, v / s \frac{1}{ T }\right) \) of first order reaction is \( -5 \times 10^{3} K \) . The value of \( E _{ a } \) of the reaction is. Choose the correct option for your answer. \( \left[\right. \) Given \( \left.R =8.314\, JK ^{-1} mol ^{-1}\right] \)
(A) \( 41.5\, kJ \,mol ^{-1} \)
(B) \( 83.0\, kJ \,mol ^{-1} \)
(C) \( 166\, kJ \,mol ^{-1} \)
(D) \( -83 \,kJ\, mol ^{-1} \)