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. |
The boiling point of glycerol is more than propanol because of |
|
Answer» HYDROGEN bonding |
|
| 2. |
The boilingpoint of glycerol is more than propanolbecause of |
|
Answer» HYDROGEN BONDING |
|
| 3. |
The boiling point of glycerol is 563K but it decomposes below 563K. It is purified by : |
|
Answer» Sublimation |
|
| 4. |
The boiling point of ethyl alcohol should be less than that of __________ |
|
Answer» PROPANE |
|
| 5. |
The boiling point of ethyl alcohol is much higher than that of dimethyl ether , though both have the same molecular weight. The reason for this is : |
|
Answer» Ether is insoluble in water |
|
| 6. |
The boiling point of ethanol is 78^(@)C and its nolal boiling point elevation constant per 1000 g is 1.15 K. A solution of 1.12 g of camphor in 32 g of ethanol has a boiling point of 78.28^(@)C. Cakculate the molecular mass of camphor. |
|
Answer» `K_(b)=1.15" K KG mol"^(-1), W_(B)=1.12 g, W_(A)=0.032 kg, M_(B)= ?` `M_(B)=(K_(b)xxW_(B))/(DeltaT_(b)xxW_(A))=((1.5" K kg mol"^(-1))xx(1.12 g))/((0.28 K)xx(0.032 Kg ))=143.75" g mol"^(-1)`. |
|
| 7. |
The Boiling point of ether is very low compared to that of same molecular weight of alcohol, because - |
|
Answer» Ether having intermolecular VANDERWALL's bond. |
|
| 9. |
The boiling point of carbon tetrachloride is 77^(@)C and its heat of vaporisation is "31 kJ mol"^(-1). Calculate the vapour pressure of carbon tetrachloride in atmospheres at 25^(@)C. |
|
Answer» Solution :Applying Clausius - Clapeyron equation `log(P_(2))/(P_(1))=(Delta_("vap.")H)/(2.303R)[(T_(2)-T_(1))/(T_(1)T_(2))]` `T_(1)=25^(@)C=25+273=298K,P_(1)=?` `T_(2)=77^(@)C=77+273=350K, p_(2)="1 atm (PRESSURE at the b. pt.)"` `Delta_("vap")H="31 kJ MOL"^(-1)="31000 J mol"^(-1),R=8.314"J K"^(-1)"mol"^(-1)` `therefore""log.(1)/(P_(1))=(31000)/(2.303xx8.314)[(350-298)/(298xx350)]` `"or"log.(1)/(P_(1))=0.8072"or"-logP_(1)=0.8072"or"logP_(1)=-0.8072=bar1.1928` `therefore""P_(1)="Antilog "bar1.1928=0.1559 atm.` |
|
| 10. |
The boiling point ofbenzene rises from 80.1^(@)C to 13.76g of biphenyl (C_(6)H_(5)-C_(6)H_(5)) is dissolved into 100 g of benzene. Calculate latent heat of vaporisation of benzene. |
|
Answer» Solution :Calculation of molal ELEVATION constant `(K_(B))` for benzene `DeltaT_(b)=(1000k_(b)w_(2))/(w_(1)M_(2))or K_(b)=(DeltaT_(b)xxw_(1)xxM_(2))/(1000xxw_(2))=((82.4-80.1)Kxx100gxx"154 g mol"^(-1))/("1000 g kg"^(-1)xx13.76g)="2.574 K kg mol"^(-1)` Calculation of `Delta_("vap")H` `K_(b)=(M_(1)RT_(0)^(2))/(1000Delta_("vap")H)or Delta_("vap")H=(M_(1)RT_(0)^(2))/(1000K_(b))=("78 g mol"^(-1)xx8.314" jK"^(-1)"mol"^(-1)xx(8.01+273)^(2)K^(2))/("1000 g kg"^(-1)xx2.574"K kg mol"^(-1))` `="31411 J mol"^(-1)=31.411" kJ mol"^(-1)` |
|
| 11. |
The boiling point of C_6H_6, CH_3OH, C_6H_5NH_2 and C_6H_5NO_2 are 80^@C,65^@C,184^@C, and 212^@C respectively. Which will show highest vapour pressure at room temperature? |
|
Answer» `C_6H_6` |
|
| 12. |
The boiling point of benzene is 353.23 K. When 1.80 gm of a nonvolatile silute was dissolved in 90 gm of benzene, the boiling point is raised to 354.11 K. The molar mass of the solute is [K_(b) for benzene = 2.53 K mol^(-1)] |
|
Answer» `5.8 g mol^(-1)` Substituting these values in expression `M_("SOLUTE")=(K_(b)xx1000xxw)/(Delta T_(b)xx W)` Where, w = WEIGHT of solute, W = weight of solvent `M_("solute")=(2.53xx1.8xx1000)/(0.88xx90)=58 gm mol^(-1)` Hence, MOLAR mass of the solute `= 58 gm mol^(-1)` |
|
| 13. |
The boiling point of benzene is 353.23 K. When 1.80 g of a non - volatile solute was dissolved in 90 g of benzene, the boiling point is raised to 354.11 K. Calculate the molar mass of the solute. K_(b) for benzene is 2.53 K kg mol^(-1). |
|
Answer» Solution :The elevation `(Delta T_(b))` in the boiling point `= 354.11 K - 353.23 K = 0.88 K` Sdubstituting these VALUES in expression `M_(2)=(1000 xx w_(2))xx (K_(b))/(Delta T_(b)xx w_(1))` we get, `M_(2)=(2.53"K kg MOL"^(-1)xx1.8 g xx1000 g kg^(-1))/(0.88K xx 90 g)` `= 58 gmol^(-1)` Therefore, molar mass of the SOLUTE, `M_(2)=58 g mol^(-1)` |
|
| 14. |
The boiling point of benzene is 353.23 K. When 1.80 g of a non-volatile solute was dissolved in 90 g benzene, the boiling point is raised to354.11 K. Calculate the molar mass of the solute. (K_(b) for benzene is 2.53 K kg mol^(-1)) |
|
Answer» Solution :Given values are: `T_(("benzene"))^(@) = 353.00 K , K_(b) = 2.53.00 K kg mol_(-1)` `T_(b("solution")) = 354.00 K` `W_("SOLUTE") = 1.80 g` `W_("solvent") = 90 g` The elevation in boiling point ,`DeltaT_(b) = T_(b("solution")) - T_(b("solvent"))^(@)` `= 354.11 - 353.23` `=0.88 K` Molar mass of solute is given as `Mw_("solute") = (K_(b) xx 1000 xx W_("solute"))/(DeltaT_(b) xx W_("solvent")` `Mw_("solute") = (2.53 xx 1000 xx 1.80)/(0.88 xx 90) = 58.0 g mol^(-1)` Hence, the molar mass of solute is `58.0 g mol^(-1)`. |
|
| 15. |
The boiling point of benzene is 353.23 K. When 1.80 g of a non-volatile solute was dissolved in 90 g of benzene, the boiling point is raised to 354.11 K. Calculate the molar mass of the solute. K_(b) for benzene is 2.53 K kg mol^(-1). |
|
Answer» Solution :Here, we are GIVEN `"" w_(2)=1.80 g, w_(1)=90 g, "" Delta T_(B)=354.11-353.23 K=0.88 K` `"" K_(b)=2.53 " K kg mol"^(-1)` Substituting these VALUES in the formula, `M_(2)=(1000 K_(b)w_(2))/(w_(1)Delta T_(b))`, we get `M_(2)=(1000 " g kg"^(-1)xx2.53" K kg mol"^(-1)xx1.80 g)/(90g XX 0.88 K)=58 "g mol"^(-1)` |
|
| 16. |
The boiling point of benzene is 353.23 K. When 1.80 g of a non - volatile non - ionisable solute was dissolved in 90 g of benzene, the boiling point raised to 354.11 K. |
|
Answer» Solution :Given `T_(b)^(0)=353.2,""w_(2)=1.80g,""w_(1)=90G,""T_(b)=354.11K,""K_(b)=2.54"K Kg mol"^(-1)` `M_(2)=(K_(b)xxw_(2)xx1000)/(DeltaT_(b)xxw_(1))=(2.53xx1.8xx1000)/(0.88xx9)="58 g/mol"` |
|
| 17. |
The boiling pointof benzene is353 .23 K. When1.80gramof non- volatile solutewasdissolvedin 90gramof benzene , theboilingpoint is raisedto 354.11 K. Calculatethe molarmass ofsolute . [K_(b)for benzene = 2.53 K kg mol^(-1)] |
|
Answer» `W_(1) = 90 g , W_(2)= 1.8 , K_(b)= 2.53 K kg mol^(-1)` Molar mass`=M_(2) = ?` `DELTA T_(b) = T_(b)- T_(b)^(o) = 354.11 - 353 .23 = 0.88K` `Delta T_(b) = K_(b) XX (W_(2) xx 1000)/(W_(1) xx M_(2))` `:. M_(2)= (K_(b) xx W_(2) xx 1000)/(Delta T_(b)xx W_(1))` ` = (2.53 xx1.8 xx 1000)/(0.88 xx90)` ` =57.5 g "mol"^(-1)` |
|
| 18. |
The boiling point of benzene at 1 atm is 80.2^@C. Calculate the enthalpy of vaporisation of benzene at its b. pt. |
| Answer» SOLUTION : `30.022 kJ.mol^(-1)` | |
| 19. |
The boiling point of an azeotropic mixture of water-ethanol is less than that of both water and ethanol. Then :- |
|
Answer» The MIXTURE will SHOW negative deviation from RAOULT's law. |
|
| 20. |
The boiling point of an azeotropic mixture of water and ethyl alcohol is less than that of theoretical value of water and alcohol mixture. Hence the mixture shows: |
|
Answer» That SOLUTION is highly saturated |
|
| 21. |
The boiling point of an aqueous solution of a non-volatile solute is 100.15^(@) C. What is the freezing point of an aqueous solution obtained by diluting the above solution with an equal volume of water? The value of K_(b) and k_(l) for water are 0.512^(@)C and 1.86^(@) C " molality"^(-1) respectively. |
|
Answer» `-0.544^(@)`C |
|
| 22. |
The boiling point of an aqueous solution of a nonvolatile solute is 100.15^@C. What is the freezing point of an aqueous solution obtained by diluting the above solution with an equal volume of water? The value of K_b and K_f for water are 0.512^@C and 1.86^@C K molality^-1: |
|
Answer» `-0.544^@C` |
|
| 23. |
The boiling point of an aqueous solution of a non-volatile solute is 100, 15^(@) C. What is the freezing point of an aqueous solution obtained by diluting the above solution with an equal volume of water? The value of K_(b) and K_(f) for water are 0.512^(@) C and 1.86^(@) "molality"^(-1) respectively. |
|
Answer» `-0.544^(@)` C |
|
| 24. |
The boiling point of an aqueous solution of a non-volatile is 100.156^(@) C. What is the freezing point of an aqueous solution obtained by diluting the above solution with an equal-voilume of water? The values of K_(b) and K_(f) for water are 0.512 and 1.86 K/molality. |
|
Answer» `-0.544^(@)` C |
|
| 25. |
Theboiling pointof anaqueoussolutionis 100.18.^(@)C. Find thefreezingpointof the solution . (Given: K_(b)= 0.52K kg mol^(-1),K_(f) = 1.86K kgmol^(-1)) |
|
Answer» `K_(o) =0.52 K kg MOL^(-1), K_(f) =1.86 K kg mol^(-1)` Boiling point ofwater`= T_(o)= 373 K` `T_(f)= ?` `Delta T_(b)= T_(b) - T_(o) =373 . 18 - 373= 0.18 K` If m is themolalityof thesolutionthen `Delta T_(b)= K_(b ) XX m " and"Delta T_( f) = K_( f) xx m` `:.(DeltaT_(f))/(Delta T_(b))= (K_(f) xx M)/(K_(b) xx M) = (K_(f))/(K_(b))` `:.Delta T_(f) = Delta T _(b) xx .(K_(f))/(K_(b))= 0.18 xx .(1.86)/(0.52) =0.6438 K` Freezingpoint ofwater = `T_(o)= 273 K` `Delta T_(f) = T_(o)- T_(f)` HENCETHE freezingpoint of thesolutionis `T_(f)=T_(o)- Delta T_(f) =273-0.6438= 272. 3562 K` ORFreezingpoint ofsolutionis - 0.6438 `.^(@)C` |
|
| 26. |
The boiling point of an aqueous solution is found to be 100.28^(@)C . Then the freezing point of the same solution is -X^(0)C . What is the value of 'X' ? |
|
Answer» |
|
| 27. |
The boiling point of alcohol is higher than that of isomeric alkane and alkyl halide, because.... |
|
Answer» They are in LIQUID state |
|
| 28. |
The boiling point of alcohol, gradually decrease as moving from 1^(@) (Primary) to 3^(@) (Tertiary) alcohol because - |
|
Answer» INTERMOLECULAR DISTANCE decreases |
|
| 29. |
The boiling point of a water containing non-valatile solute is 101.04 ^(@)C of 2 molal solution, the ebullioscopic constant of water is |
|
Answer» 0.52 K . Kg `"mol"^(-1)` `T^(@) = 100^(@)C = 373 K, m=2 "MOLAL"` `:. Delta T_(b) = K_(b) XX m` `K_(b) = (Delta T_(b))/m = (374.04-373)/2=1.01/2=0.52` K. Kg `"mol"^(-1)` |
|
| 30. |
The boiling point of alcohol are…… than corresponding thiols |
|
Answer» More |
|
| 31. |
The boiling point of a solvent containing non volatile solute : |
|
Answer» is depressed |
|
| 32. |
The boiling point of a solvent containing a non-volatile solute |
|
Answer» is DEPRESSED |
|
| 33. |
The boiling point of a solution of 0.11 of a substance in 15g of ether was found to be 0.1^(@)C higher than that of pure ether. The molecular weight of the substance will be (K_(b)=2.16) : |
|
Answer» 148 `K_(b)=2.16, w=0.11, W=15 g, Delta T_(b) =0.1` `m=(2.16xx0.11xx1000)/(0.1xx15)=158.40 ~= 158`. |
|
| 34. |
The boiling point of a solution containing 2.62 g of a substance A in 100 g of water is higher by 0.0512^(@)C than the boiling point of pure water. The molar mass of the substance ( K_(b)=5.12Km^(-1) ) is : |
|
Answer» 131 `=(5.12xx1000xx2.62)/(100 xx 0.0512)=2620` |
|
| 35. |
The boiling point of a compound is raised by |
|
Answer» volatility of compound |
|
| 36. |
The boiling point of 0.2molkg^(-1)solution of X in water is greater than equimolal solution of Y in water.Which one of the following statement is true in the case? |
|
Answer» Molecular MASS of X is less than the molecular mass of Y For equilbrium solutions, elevation in boiling point will be higher of solution undergoes dissociation i.e.,`igt1` |
|
| 37. |
The boiling point of 0.2 mol "kg"^(-1) solution of X in water is greater than equimolal solution of Y in water, Which one of the following statements is true in the case ? |
|
Answer» MOLECULAR mass of X is less than the molecular mass of Y. |
|
| 38. |
The boiling point of 0.2 mol kg^(-1) solution of X in water is greater than equimolal solution of Y in water. Which one of the following statements is true in this case ? |
|
Answer» X is undergoing dissociation in water. same SOLVENT so, `K_(b)` is same m is same (given) `i_(x).K_(b).m gt i_(y).K_(b).m rArr i_(x)gt i_(y)` so, X is undergoing dissociation in water. |
|
| 39. |
The boiling point of "0.2 mol kg"^(-1) solution of X in water is greater than equimolal solution of Y in water. Which one of the following statements is true in this case? |
|
Answer» MOLECULAR mass of X is less than molecular mass of Y |
|
| 40. |
The boiling point of 0.2 mol kg^(-1) solution of X in water is greater than equimolal soltuion of Y is water. Which one of the following stamtements is true in this case |
|
Answer» MOLECULAR mass of X is greater than the molecular of Y |
|
| 41. |
The boiling point elevation and the freezing point depression of solutions have a number of practical applications. Ethylene glycol (CH_(2)OH. CH_(2)OH) is used in automobile radiators as an antifreeze because it lowers the freezing point of the coolant. The same substance also helps to prevent the radiator coolant from boiling away by elevating the boiling point. Ethylene glycol has low vapour pressure. We can also use glycerol as antifreeze. For the boiling point elevation to occur the solute must be non-volatile, but no such restriction applies to freezing point depression. For example mthanol (CH_(3)OH), a fairly volatile liquid that boils only at 65^(@)C is sometimes used as antifreeze in automobile radiators. If cost of glycerol, glycol and methanol are same, then the sequence of economy to use these compounds as antifreeze will be: |
|
Answer» GLYCEROL `GT` GLYCOL `gt` methanol |
|
| 42. |
The boiling point of 0.1 molal aqueous solution of urea is 100.18^(@)C at 1 atm. The molal elevation constant of water is |
|
Answer» `1.8` |
|
| 43. |
The boiling point of 0.1 m K_(4)[Fe(CN)_(6)] is expected to be (K_(b) for water =0.52K kg "mol" ^(-1)) |
|
Answer» `100.52^(@)C` |
|
| 44. |
The boiling point of 0.1 molal aqueous solution of urea is 100.18 ^(@)C atm. The molal elevation constant of water is |
|
Answer» 1.8 |
|
| 45. |
The boiling point elevation for toluene is 3.32 K kg "mol"^(-1) . The normal boiling point of toluence is 110.7^(@)C . The enthalpy of vapourization of the toluene would be nearly : |
|
Answer» `17.oKJ "MOL"^(-1)` |
|
| 46. |
The boiling point elevation and the freezing point depression of solutions have a number of practical applications. Ethylene glycol (CH_(2)OH. CH_(2)OH) is used in automobile radiators as an antifreeze because it lowers the freezing point of the coolant. The same substance also helps to prevent the radiator coolant from boiling away by elevating the boiling point. Ethylene glycol has low vapour pressure. We can also use glycerol as antifreeze. For the boiling point elevation to occur the solute must be non-volatile, but no such restriction applies to freezing point depression. For example mthanol (CH_(3)OH), a fairly volatile liquid that boils only at 65^(@)C is sometimes used as antifreeze in automobile radiators. 620g glycol is added to 4kg water in the radiator of a car. What amount of ice will separate out at -6^(@)C ? K_(f) = 1.86K kg mol^(-1). |
|
Answer» 800g |
|
| 47. |
The boiling point elevation and the freezing point depression of solutions have a number of practical applications. Ethylene glycol (CH_(2)OH. CH_(2)OH) is used in automobile radiators as an antifreeze because it lowers the freezing point of the coolant. The same substance also helps to prevent the radiator coolant from boiling away by elevating the boiling point. Ethylene glycol has low vapour pressure. We can also use glycerol as antifreeze. For the boiling point elevation to occur the solute must be non-volatile, but no such restriction applies to freezing point depression. For example mthanol (CH_(3)OH), a fairly volatile liquid that boils only at 65^(@)C is sometimes used as antifreeze in automobile radiators. 124g each of the two reagents glycol and glycerol are added in 5kg water of the radiators in the two cars. Which of the following statements is wrong? |
|
Answer» Both will act as antifreeze |
|
| 48. |
The boiling of an aqueous of non volatile & non electrolytic solute is 100.15^(@)C. How many times the solution is diluted by water to get freezing point of resultant solution as -0272^(@)C given K_(b) and K_(f) of water are 0.512 and 1.86 K kg "mol"^(-1) |
|
Answer» |
|
| 49. |
The boiling point and melting point of inert gases are |
|
Answer» high |
|
| 50. |
The boiling point of 0.2 mol kg^(-1) solution of X in water is greater than equimolal solution of Y in water. Which of the following statements is true in this case? |
|
Answer» Molecular mass of X is less than that of Y |
|