41.

The role of a catalyst is to change :

• enthalpy of reaction

• equilibrium constant

• activation energy of reaction

• Gibbs energy of reaction

Which one of the following options is not correct for the decomposition reaction of NH₃ ?

2NH₃ (g) $\underset{\mathrm{Pt} \mathrm{catalyst}}{\overset{1130 \mathrm{K} , \mathrm{at} \mathrm{high} \mathrm{p}}{\to }}$ N₂ (g) + 3H₂ (g)

• Rate of reaction = rate constant

• Further increase in pressure will change the rate of reaction

• Rate of decomposition of NH₃ will remain constant until NH₃ disappears completely

• Rate of reaction depends on concentration of NH₃

For the reaction , aA + bB $\to$ cC , if -3$\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dT}}$ = -3$\frac{\mathrm{d}\left[\mathrm{B}\right]}{\mathrm{dt}}$ = +1.5$\frac{\mathrm{d}\left[\mathrm{C}\right]}{\mathrm{dt}}$ then a , b , c respectively are :

• 1 , 3 , 2

• 1 , 2 , 3

• 3 , 2 , 1

• 3 , 1 , 2

60 g of urea is dissolved in 1100 g solution. To keep $∆$Tf/Kf as 1 mol kg-1 water separated in the form of ice is :

• 40 g

• 60 g

• 100 g

• 200 g

Osmosis involved in :

• excretion of urine

• interchange of nutrients and waste products betweeen tissue cells and their surroundings

• in both cases

• None of the above

Vapour density of PCl₅ (g) dissociating into PCl₃ (g) and Cl₂ (g) is 100. Hence, van't Hoff factor for the case :

PCl₅ (g) $\rightleftharpoons$ PCl₃ (g) + Cl₂ (g) is :

• 1.85

• 3.70

• 1.085

• 1.0425

Ionic conductances of H⁺ and S${\mathrm{O}}_4^{2-}$ at infinite dilution are x and y S cm² equiv^-1 . Hence , equivalent conductance of H₂SO₄ at infinite dilution is :

• (x + y)

• 2(x + y)

• 2x + y

• x + 2y

In the refining ofsilver by electrolytic method, what will be the weight of 100 g Ag anode if 5A current is passed for hours ? The purity of silver anode is 95% by weight.

• 42.91 g

• 57.59 g

• 13.16 g

• 36.38 g

Salt bridge contains :

• calomel

• corrosive sublimate

• agar-agar paste

• H₂O

The pK_a of phenol is 10. Which of the following bases will deprotonate phenol completely?

NaNH₂ (_PK_a of NH₃ = 35) , (_PK_b of H₂O = 16) , NaNH₂ (_pK_a of N${\mathrm{H}}_4^{+}$ = 10) , NaOOCH₃ (_pK_b of CH₃COOH =5)

• NaNH₂

• NH₃

• NaNH₂ and NaOH

• NH₃ and NaOCOCH₃