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This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
At 25^(@)C, pH of a 10^(-8)M aqueous KOH solution will be |
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Answer» `6.0` `= ~ 6.98` `:. PH = 14 - 6.98 = 7.02` |
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| 2. |
At 25^(@)C, K_(sp) value for Hg_2Br_2 and Hg_2I_2 are 1.3xx10^(-22) and 1.1xx10^(-18) respectively.In a solution containing KBr and KI, concentration of each is 0.01(M). To this solution, a Hg_2(NO_3)_2 solution is added drop by drop. The concentration of the remaining Br^- ions at the K_a(CH_3COOH)=1.8xx10^(-5) then increasing order of the pH values of the solutions- |
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Answer» `3.2xx10^(-4)(M)` |
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| 3. |
At 25^(@)C, K_b for CH_3COO^(0-) ion in water is 5.55xx10^(-10) If 100mL of 0.025(M) HCl solution is added to 50mL of 0.1(M) solution of CH_3COONa, pH of the resulting solution will be- |
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Answer» 3.82 |
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| 4. |
At 25^(@)C, for the reaction, H^(+)(aq)+OH^(-)(aq)toH_(2)O(l),DeltaH^(0)=-57.3kJ*mol^(-1). If the ionisation enthalpy of HCN in water by 45.2 kJ*mol^(-1), then the standard heat of reaction (in kJ*mol^(-1)) for the reaction, HCN(aq)+NaOH(aq)to NaCN(aq)+H_(2)O(l), in dilute aqueous solution is- |
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Answer» `-113.5` |
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| 5. |
At 25^(@)C for a given solution M=m, then at 50^(@)C the correct relationship is |
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Answer» `M=m` |
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| 7. |
At 25^@Cequivalent conductance of a week acid HAc is16.2 "ohm"^(-1) cm^(2) eq^(-1).If the ionic conductances of Ac^(-) and H^(+)at infinite dilution are respectively 40.9 and 349.8 "ohm"^(-1)cm^(2)eq^(-1)., calculate the percentage dissociation of the week acid at 25^@C. |
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Answer» |
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| 8. |
At 25^(@)C aqueous solution of glucose (molecular weight = 180 g mol^(-1)) is isotonic with a 2% aqueous solution containing an unknown solute. What is the molecular weight of the unknown solute |
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Answer» 60 `therefore (m_(1))/(M_(1))=(m_(2))/(M_(2))` or `(5)/(180)=(2)/(M_(2))rArr M_(2)=72`. |
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| 9. |
At 25^(@)C and 1 bar which one of the following has a non zero DeltaH_(f)^(@)? |
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Answer» `Br_(2)(1)`<BR>C (graphite) |
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| 10. |
At 25^(@)C, a 0.1m solution of CH_(3)COOH is 1.35% dissociated. Calculate the freezing point and osmotic pressure of the solution. Compare your results with those expected under conditions of no dissociation . K_(f) for water =1.86^(@)Cm^(-1). |
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Answer» `=1.86xx0.2` `=0.372` We have `i=("OBSERVED colligative property")/("normal colligative property")`………..(Eqn 9) `=(0.68)/(0.372)=1.83` Again, `i=("observed osmotic pressure")/("normal osmatic pressure")` `:.` observed osmotic pressure `=i xx` normal osmotic pressure `=i xx cRT`............(Eqn 6) `=1.83xx0.2xx0.082xx273` `=8.2` atm |
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| 11. |
At 25^(@)C a solution containing 0.2g of polyisobutylene in 100 "cc" of benzene, developed a rise of 2.4mm at osmotic equilibrium . Calculate the molecular weight of polyisobutylene if the density of the solution is 0.88g//"cc" |
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Answer» |
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| 12. |
Two oxides of nitrogen, NO and NO_(2) react together at 253 K and form a compound of nitrongen, X. X reacts with water to yield another compound of nitrogen Y. the shape of the anion of Y molecule is |
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Answer» TETRAHEDRAL |
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| 13. |
At 250^@C the half life for the decomposition of N_2O_5 is 5.7 hr and is independent of initial pressure of N_2O_5. Thespecific rate constant is: |
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Answer» `0.693//5.7` |
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| 14. |
At 25^(@) the specific conductance of a saturated solution of AgCl after subtracting the specific conducatnce of water is 1.82 xx 10^(4) Sm^(-1). The molar conductance at infinite dilution of AgNO_(3), HNO_(3) and HCl are respectively 133.0 xx 10^(-4), 421.0 xx 10^(-4) and 426 xx 10^(-4) S m^(2) "mol"^(-1). Find the solubility of AgCl. Write down the half cell reaction and calculate standard reduction potential for that the half Pt | 50mL 0.5 M KCl solution in which few drops of 0.1 M E_(Ag, Ag)^(0)=0.80V. |
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Answer» 0.224 V Half cell REACTIONS `AgCl(s)+e^(-) to Ag(s)+Cl^(-) (aq)` |
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| 15. |
At 250^(@)C , the half life for the decomposition of N_(2)O_(5) is 5.7 hour and is independent of initial pressure of N_(2)O_(5). The specific rate constant is |
| Answer» Answer :A | |
| 16. |
At 25^(@) the solubility product of a salt AB_2 in water is 4.0xx10^(15). If 0.1 mol of A^(2-) ions is added to 1 L of asaturated solution of the salt (assuming volume of the solution does not change on addition of A ^(2-) ions), then |
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Answer» SOLUBILITY product of `AB_2` will increase |
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| 17. |
At 25^(@)C the activation energy for a catalysed reactionis 126KJ mol^(-1) and for uncatalysedreactionis 350 KJ mol^(-1) . Howmany timesthe ratesis increased in thepresenceof catalyst ? |
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Answer» Solution :According to Arrhenius equation, the specific rates (k) of a REACTION with different ACTIVATION energies `(E_(a))` are given as `log.(k_(1))/(k_(2))=(1)/(2.303RT)[E_(a_(2))-E_(a_(1))]=((350-162)1000)/(2.303xx8.314xx298)` THEREFORE the RATIO of rates, `k_(1)//k_(2)=8.9xx10^(32)`. In the PRESENCE of a catalyst rate is increased by `8.9xx10^(32)` times. |
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| 18. |
At 25^(@) temperature, the solubility products for BaCrO_4 and SrCrO_4 salts are 2.4xx10^(-10) and 3.6xx10^(-6) respectively. If an aqueous solution of K_2CrO_4 is added drop by drop to an aqueous solution containing Ba^(2+) and Sr^(2+) ions with concentrations of 10^(-4) and 10^(-3)(M) respectively then- |
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Answer» `BaCrO_4` will be precipitated first |
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| 19. |
At 25^(@), K_a for a weak acid, HA in water, is 10^(-5), V_2mL of 0.1(M) NaOH solution is added to V_1mL of 0.1(M) solution of HA. How many time would V_1be of V_2 so that pH of the solution be 6- |
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Answer» 2 times |
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| 20. |
At 25^(@) , K_(sp) for Al(OH)_3 in water is 2xx10^(-33). In an aqueous solution of PH=13, the solubility of Al(OH)_3 is 2xx10^(-x). The value of x is- |
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Answer» 10 |
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| 21. |
At 25^(@), K_b for CN^- (conjugate base of HCN) is 2.5xx10^(-5). If 25 mL of 0.01(M) aqueous NaOH solution isadded to 50mL of 0.01(M) HCN solution, then- |
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Answer» PH of the resulting SOLUTION is 11.2 |
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| 22. |
At 25^(@) C, the standard emf of cell having reactions involving two electron exchange is found to be 0.295 V. The equilibrium constant of the reaction is |
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Answer» `29.5 XX 10^(-2)` |
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| 23. |
At 25^@ C, the solubility product of a salt of MX_2 type is 3.2 xx10^(-8) in water. The solubility (in mol/L) of MX_2 in water at the same temperature will be |
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Answer» `1.2 XX 10^(-3)` ` K_(sp )= S xx (2s)^2 =4S^3` ` 4S^3 = 3.2 xx 10^(-8)` ` S= SQRT((3.2 xx 10^(-8))/(4))` ` S= 2 xx 10^(-3)` |
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| 24. |
At 25 ^(@)C , the molar conductance of 0.007 M hydrofluoric acid is 150 mho cm^(2) mol^(-1) and its Lambda_(m)^(@) = 500 mho cm^(2) mol^(-1) . The value of the dissociation constant of the acid at the given concentration at 25^(@)C is |
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Answer» `7 xx 10^(-4)` M `Lambda_(m)^(@) = 500 mho cm^(2) mol^(-1)` Degree of DISSOCIATION `(alpha) = (Lambda_m)/(Lambda_m^@) = (150)/(500) =0.3` `""HF hArr H^(+) + F^(-)` C "" 0 "" 0` `Final : C - Calpha""C alpha ""Calpha` `therefore K_(a)= (C_(alpha).C_(alpha))/(C-C_(alpha)) = (Calpha^(2))/(1 - alpha)` `K_(a) = (7 xx10^(-3) xx (0.3)^(2))/(1-0.3)=(7xx 10^(-3)xx9 xx 10^(-2))/(0.7)` `rArr K_(a) = (7xx9xx 10^(-5))/(7XX10^(-1)) = 9 xx10^(-4) M` |
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| 25. |
At 25^@ C, the ionic mobility of CH_3COO^(-), H^+ are respectively 4.1 xx 10^(-4), 3.63 xx 10^(-3) cm/sec. The conductivity of 0.001M CH_3COOH is 5xx10^(-5)S.cm^(-1). Dissociation constant of CH_3 COOHis |
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Answer» `1.64 xx 10^(-5)` |
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| 26. |
At 25^(@) C, the dissociation constant of a weak monoprotic acid, HA(K_(a) is numerically equal to the dissociation constant of its conjugate base, A^(-)(K_(b)). Which of the following statement(s) is are correct? |
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Answer» The DISSOCIATION constatn of the ACID, HA is `10^(-7) at 25^(@)` C |
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| 27. |
At 25^@ C, pH of a 10^(-8) M aqueous KOH solution will be |
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Answer» `6.0 ` `thereforepOH=- log[10^(-8 ) + 10^(-7)]` ` ~~ 6.98 ` ` THEREFORE pH=14 - 6.98= 7.02` |
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| 28. |
At 25^(@) C molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 ohm^(-1) cm^(2) mol^(-1) and at infinite dilution its molar conductance is 238 ohm^(-1) cm^(2) mol^(-1) . The degree of ionisation of ammonium hydroxide at the same concentration and temperature is : |
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Answer» `4.008 %` |
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| 29. |
At 25°C the specific conductance of a 1N solution of KCl is 0.002765 mho. The resistance of cell is 400 Omega. The cell constant is: |
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Answer» `0.815 CM^(–1)` |
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| 30. |
At 227^(@)C , the presence of catalyst causes the activation energy of a reaction to decrease by 4.606 K cal. The rateof the reaction will be increased by : - |
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Answer» 2 TIMES |
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| 31. |
At 21.5^@C and a total pressure of 0.0787 atm, N_2O_4is 48.3% dissociated into NO_2. Calculate K_cfor the reaction: N_2O(g) iff 2NO_2(g).At what total pressure will the per cent dissociation be 10%? |
| Answer» SOLUTION :0.00396, 2.371 ATM | |
| 32. |
At 20^(@)C, The vapour pressure of liquid A is 22 mm of Hg and that of pure liquid B is 75 mm of Hg. What is thecomposition of these somponents in the solution that has the vapour presure of 48.5 mm of Hg at this tempreture ? (Assuming ideal solution behaviour). |
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Answer» `P_(A)=P_(A)^(@)+P_(A)=P_(A)^(@)x_(A)orP_(A)=(22mm)x_(A)` `P_(B)=P_(B)^(@)x_(B)orP_(B)=(22 mm)x_(B)=(75 mm)(1-x_(A))` According to availble data : `P_(A)+P_(B)=48.55 mm` `THEREFORE (22mm)x_(A)+(75 mm)(1-x_(A))=48.55 mm` `therefore (-53 mm)x_(A)=-26.45 mm` or `x_(A)((-26.45mm)/(-53mm))=0.5` Thus `x_(A)=0.5" and "x_(B)=(1-0.5)=0.5` `therefore "Two liquids have EQUAL moles of A and B".` |
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| 33. |
At 20^(@)C, the osmotic pressure of urea solution is 400 mm. The solution is diluted and the temperature is raised to 35^(@)C, when the osmotic pressure is found to105.3 mm. Determine the extent of dilution……… |
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Answer» |
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| 34. |
At 20%(@)C the vapour pressure of ether is 442 mmHg. When 6.1g of a substance is dissolved in 50g of ether (mo.wt.74) the vapour pressure falls to 410mm. What is the molecular weight of the substance ? |
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Answer» |
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| 35. |
At 20^(@)C, the solubility of N_(2) in waer is 0.0150 gL^(-1) when the partial pressure of N_(2) is 580 mm Hg. What will be the solubility of N_(2) in water at 20^(@)C when its partial pressure is 800 mm Hg ? |
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Answer» `P_(1)=580mm Hg, P_(2)=800 MMHG` According to Henry'a LAW, `C_(2)/C_(1)=P_(2)/P_(1)or C_(2)=P_(2)/P_(1)xxC_(1)` `C_(2)=((800MM))/((580mm))xx(0.0150 gL^(-1))=0.0207 gL^(-1).` |
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| 36. |
At 20^@C, the vapour pressure of diethyl ether is 442mm. When 6.4g. of a non-volatile solute is dissolved in 50g. of ether, the vapour pressure falls to 410mm. The Molecular weight of the solute is |
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Answer» 150 |
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| 37. |
At 20^(@)C, the Ag^(+) ion concentation in a saturated solution of Ag_(2)CrO_(4) is 1.5 xx 10^(-4) mole/litre. At 20^(@)C, the solubility product of Ag_(2)CrO_(4) would be |
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Answer» `3.3750 xx 10^(-12)` `K_(sp) = 4S^(3)` given `2S = 1.5 xx 10^(-4)` `:. K_(sp) = (2S)^(2) xx S` `= (1.5 xx 10^(-4))^(2) xx ((1.5 xx 10^(-4))/(2)) = 1.6875 xx 10^(-12)` |
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| 38. |
At 20^@Cthe [Ag^+] in a saturated solution of Ag_2CrO_4 is 1.5xx10^(-4) M find the solubility product of Ag_2CrO_4 : |
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Answer» `3.375xx10^(-12)` |
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| 39. |
At 200^(@)C, the velocity of hydrogen molecules is 2.4xx10^(5) cm/sec. In this case the de-Broglie wavelength is about |
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Answer» `1Å` `=2.4xx10^(3)`m/sec Mass of HYDROGE `=2/(60.2xx10^(23))` `=3.32xx10^(-24)m-3.32xx10^(-27)kg` `lamda=h/(mv)=(6.6xx10^(-34))/(3.32xx10^(-27)xx2.4xx10^(3))` `=0.83xx10^(-10)m=1Å` |
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| 40. |
At 200^(@)C, the equilibrium N_(2)O_(4)(g)hArr2NO_(2)(g) is achieved in the following two pathways: (i) 0.1 mol N_(2)O_(4) is heated in a closed vassel of 1 L volume. (ii) a mixture of 0.05 mol N_(2)O_(4)(g) and 0.05 mol NO_(2)(g) is heated at 200^(@)C in a closed vessel of 1 L volume. in these two cases, will the equilibrium concentrations of N_(2)O_(4)(g) and NO_(2)(g) and the values of equilibrium constants be the same? |
| Answer» SOLUTION :The value of equilibrium constant of a reaction depends only on TEMPERATURE it does not depend on the initial CONCENTRATIONS of the reactants. Since temperature is the same for both experiments, the value of equilibrium constant will be the same in both cases. the initial concentrations of the reactant(s) in the two experiment are not the same. As a RESULT, the molar concentrations of `N_(2)O_(4)(g) and NO_(2)(g)` at equilibrium will be different in the two experiments. | |
| 41. |
At 193^(@)C , the ratelaw for the reaction2Cl_(2)O to 2Cl_(2) + O_(2) is rate = k[Cl_(2)O]^(2) . (a) How the ratechangesif [Cl_(2)O]is raised to therefold of the original ? (b) How should [Cl_(2)O] be changed in orderto order to double the rate ? |
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Answer» Solution :Original RATE is given as, rate `=k[Cl_(2)O]^(2)` (a) Rate with threefold concentration of `Cl_(2)O` is k `[3Cl_(2)O]^(2)`. This is NINE times to the original rate. (b) With `[Cl_(2)O]` the rate is `R=k[Cl_(2)O)^(2)`. Requirement is that .r. should be doubled at concentration of, `Cl_(2)O` as `x`. `(2r)/(r)=(kx^(2))/(k[Cl_(1)O]^(2))("or")x=sqrt(2)[Cl_(2)O]` The concentration of `Cl_(2)O` should be increased by `1.414` times. |
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| 42. |
At 18^(@)C the mobilities of NH_(4)^(+) and ClO_(4)^(-) ions are 6.6 xx 10^(-4) and 5.7 xx 10^(-4) cm^(2) " volt"^(-1) s^(-1) at infinite dilution. Calculate equivalent conductance of ammonium chlorate solution. |
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Answer» Solution :From Kohlrausch.s LAW, we have, `Lambda_(NH_(4)ClO_(4))^(@) = lambda_(NH_(4))^(@) + lambda_(ClO_(4)^(-))^(@)` `= F U_(NH_(4))^(+) + FU_(ClO_(4)^(-))^(@)` `= F = (U_(NH_(4))^(@) + F U_(ClO_(4)^(-))^(@))` `=96500 (6.6 xx 10^(-4) + 5.7 xx 10^(-4))` `= 118.67 "mho cm"^(2)`. |
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| 43. |
At 18^(@)C, the conductance of H^(+) and CH_(3)COO^(-) at infinite dilution are 315 and 35 mho cm^(2)eq^(-1) respectively. The equivalent conductivity of CH_(3)COOH at infinite dilution is ______mho cm^(2)eq^(-1) |
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Answer» 350 |
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| 44. |
At 18^(@)C the heat of solution of anhydrous CuSO_(4) in a large volume of water is -15.90 kcal per mole while that of CuSO_(4).5H_(2)O is 2.75 kcal per mole. What is the heat of hydration of CuSO_(4) ? |
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Answer» Solution :GIVEN that, (i) `CuSO_(4)(s)+aq to CuSO_(4)(aq),DELTAH=-15.9 "kcal"` (ii) `CuSO_(4).5H_(2)O+aq to CuSO_(4)(aq),DeltaH=+2.75 "kcal"` We have to calculate `DeltaH` of the equation : `CuSO_(4)(s)+aq to CuSO_(4).5H_(2)O,DeltaH=?` Applying the inspection method, [Eqn (i)- Eqn (ii)], We get, `CuSO_(4)(s)+aq to CuSO_(4).5H_(2)O,DeltaH=-15.9-2.75=-18.65 "kcal"` |
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| 45. |
At 18^(@)C, the conductance of H^(+) ions and CH_(3)COO^(-) ions at infinite dilution are 315 and 35 mho cm^(2) eq^(-1) respectively. The equivalent conductance of CH_(3)COOH at infinite dilution is (mho cm^(2) " equiv"^(-1)) |
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Answer» 280 `=350" mho "cm^(2)"equiv"^(-1)`. |
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| 46. |
At 1300 k, and 1 atm pressure, Areaction was performed in 4 litre container as follows 2SO_2+O_2 hArr 2SO_3 If K_c =40 and the mixture was supposed contain 2, 3 and 5 mole of SO_2, O_2 and SO_3 respectively at any point of time of reaction. Then what will be the direction of the reaction ? |
| Answer» SOLUTION : REACTION will PROCEED in FORWARD DIRECTION | |
| 47. |
At 1400 K, K_c=2.5xx10^(-3) for the reaction CH_4(g)+2H_2S(g)hArrCS_2(g)+4H_2(g).A 10.0 L reaction vessel at 1400 K contains 2.00 mole of CH_4.3.0 mole of CS_2,3.0 mole of H_2 and 4.0 mole of H_2S.Then |
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Answer» This reaction is at equilibrium with above concentrations So, reaction will proceed in backward direction |
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| 48. |
At 127^oC, heat of fusion of a compound is 4.8kJ/mol. Entropy change for the process is |
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Answer» `37.8 JK^-1mol^-1` |
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| 49. |
At 10^(@)C, the osmotic pressure of urea solution is 500 mm. The solution is diluted and the temperature is raised to 25^(@)C when the osmotic pressure is found to be 105.3 mm. Calculate the extent of dilution. |
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Answer» Solution :Suppose initially the volume of solution `=V_(1)` `"Given"T=10+273K = 283 K, pi=(500)/(7760)" atm"` `pi="CRT"=(pi)/(V)=RT""therefore""(500)/(600)=(n)/(V_(1))Rxx283"…(i)"` After dilution, suppose volume of solution `=V_(2)` `"Given"T=25+273K=298K, pi=(105.3)/(760)" atm"` `therefore""(105.3)/(760)=(n)/(V_(2))Rxx298"(n = no. of moles which remains same)...(ii)"` Dividing eqn. (i) by eqn. (ii) `(500)/(105.3)=(V_(2))/(V_(1))xx(283)/(293)"or"(V_(2))/(V_(1))=(500)/(105.3)xx(298)/(283)=5"or"V_(2)=5V_(1)` Thus, solution has been diluted 5 times. |
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| 50. |
At 10^(@)C the osmotic pressure of a urea solution is 500mm. The solution is diluted and the temperature is raised to 25^(@)C, when the osmotic pressure is found to be 105.3mm. Determine the extent of dilution |
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Answer» SOLUTION :Suppose `V_(1)` litres of the solution CONTAINS n moles of the solute at `10^(@)C` which was DILUTED to `V_(2)` litres at `25^(@)C`. Thus we have, `{:(,,(500)/(760)=(n)/(V_(1))xx0.082xx283),("and",,(105.3)/(760)=(n)/(V_(2))xx0.082xx298):}` Dividing (1) by (2), we get `(V_(2))/(V_(1))=5` Thus the solution was diluted 5 times |
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