52671 + Interview Questions in Chemistry in Class 11

1.	An atom of an element contains 29 electrons and 35 neutrons. Deduce (i) the number of protons and (ii) the electronic configuration of the element.
Answer» Solution :For neutral atom, number of protons = number of electrons `=29` THUS, atomic number of the element `=29` Electronic configuration of element with `Z=29` will be : `1s^(2) 2s^(2) 2p^(6) 3s^(2) 3P^(6) 3d^(10) 4s^(1) or [Ar]^(18) 3d^(10) 4s^(1)`, i.e., `._(29)CU`. Mass number = No. of protons + No. of NEUTRONS `=29+35=64`

Discussion

2.	An atomof anelementcontains29electron and 35neutrons .Deduce(i) The number ofprotonsand (ii)the electronicconfigurationofthe element .
Answer» Solution :(i) Numberof ELECTRON= no of PROTON = 29 (ii) Z=29so electronconfiguratin `1s^(2)2s^(2) 2p^(6)3s^(2) 3P^(6) 3d^(10)4S^(1)` 3dsubshellis complete

Discussion

3.	An atom is 40.08 times as heavier as 1/12 mass of an atom of Cl_2. What is its atomic mass ?
Answer» ANSWER :40.08

Discussion

4.	An atom having atomic mass number 13 and 7 neutrons. What is the atomic number of the atom ?
Answer» SOLUTION :`A = 13, N=7` As `A = n + p:. p = A -n = 13 - 7 = 6`. Hence, `Z = p = 6`

Discussion

5.	An atomhas the electronicconfigurationof1s^(2) ,2s^(2) 2p^(6),3s^(2) 3d^(10) , 4s^(2) 4p^(5).Itsatomicweight is 80 . Its atomicnumberand thenumberof neutronsin itsnucleusshall be
Answer» 35 and 45 45 and 35 40 and 40 30 and50 Solution :`._(35)Br^(8) =1s^(2) 2s^(2) 3S^(6 ) 3d^(10)4P^(5)` n=A-Z=80 - 35 = 45 Atomicnumberof is 35 and no of neutronis45.

Discussion

6.	An atom having atom ic m ass num ber 13 has 7 neutrons. W hat is the atom ic n u m b er of the atom ?
Answer» Solution :N EUTRON is neutral so, no deflection from the p ath on passing through an electric field. Proton, cathode RAYS an d ELECTRON being the charged particle will show deflection from the p ath on passing through an electric field.

Discussion

7.	An atom has a mass number of 23 and atomic number 11. The number of protons are ______
Answer» 23 11 12 44 Answer :B

Discussion

8.	An atom of an element 'A' has three electrons in its outermost shell and that of 'B' has six electrons in the outrer most shell. The formula of the compound formed between these two elements is
Answer» `A_(3)B_(4)` `A_(2)B_(3)` `A_(3)B_(2)` `A_(2)B` ANSWER :B

Discussion

9.	An atom A belongs to IIA group and another atm B belongs to VA group. The fomula of the compound formed is
Answer» `A_(3)B_(6)` `A_(2)B` `A_(2)B_(3)` `A_(3)B_(2)` ANSWER :D

Discussion

10.	An atom differs from its ion in
Answer» <P>NUCLEAR charge Mass number Number of ELECTRONS Number of neutrons Solution :Atom and ion will have n(n) , n(p) same

Discussion

11.	An athlete is given 100 g of glucose ( C_(6)H_(12)O_(6)) of energy equivalent to 1560 kJ . He utilizes50 percent of this gained energy in the event. In order to avoid storage of energyin the body, calculate the weight of water thehe would need to perspire. The enthalpyof evaporation of wateris 44 kJ // mol .
Answer» Solution :Energy left unutilized `=(1560)/(2)kJ = 780kJ` For losing 44kJ of energy, WATER to be EVAPORATED `= 1` MOLE`= 18G` `:. `For losing 780 kJ of energy,water to beevaporated`= ( 18)/( 44) xx780 g = 319 g`

Discussion

12.	An athelete is given 100 g of glucose (C_(6)H_(12)O_(6)) of energy equivalent to 1560 kJ. He utilizes 50% of this gained energy in the event. In order to avoid storage of energy in body , the weight of water he would need to perspire is : (The enthalpy of evaporation of water is 44 kJ//mole)
Answer» 319 g 422 g 293 g 378 g Answer :A

Discussion

13.	An astronaut receives the energy required in his body by the combustion of 34gm of sucrose per hour. How much oxygen he has to carry along with him for his energy requirement in a day?
Answer» SOLUTION :916.21 GM

Discussion

14.	An astronaut receives the energy required in his body by the combustion of 34g of sucrose per hour. How much oxygen he has to carry along with him for his energy requirement in a day?
Answer» ANSWER :916.2g

Discussion

15.	An aromatic molecule will
Answer» have `4npi`-electrons have `(4n+2)` `pi`- electrons be planar be cyclic Solution :An aromatic will have (B) (4n+2) electrons (by HUCKEL's rule) (C) planar structure (DUE to resonance). (D) cyclic structure (due to presence of `sp^(2)`-hybdird CARBON atoms.

Discussion

16.	An aromatic compound having C_(7)H_(8)O as the molecular formula has.................isomers.
Answer» ANSWER :FIVE ISOMERS, i.e., benzyl alcohol, ANISOLE, o-m- and p-cresols

Discussion

17.	An aromatic compound has molecular formula C_(7)H_(8)O. The number of phenolic isomers for this compound is
Answer» 4 3 5 6 Solution :

Discussion

18.	An archeological speciment containing .^(14)C gives 40 counts in 5 mintues per gram of carbon.A specimen of freshlycut wood gives 20.3 counts per gram of carbon per minute. The counter used recorded a background count of 5 counts per mintue in absence of any .^(14)C containing sample. What is the age of the speciment? (T_(50) of .^(14)C = 5668 year)
Answer» ANSWER :`13327.8` YEAR

Discussion

19.	An aqueous solution of sucrose, C_(12)H_(22)O_(11), containing 23.2g/L has an osmotic pressure of 2.38 atmosphere at 17^(@)C, For an aqueous solution of glucose, C_(6)H_(12)O_(6), to be isotonic with this solution, it would have :
Answer» 34.3 g/L 17.1 g/L 18.0 g/L 36.0 g/L of glucose Answer :C

Discussion

20.	An aqueous solution of sodium sulphate is electrolysed using inert electrodes. The products at the cathode and anode are respectively
Answer» `H_(2), O_(2)` `O_(2), H_(2)` `O_(2), Na` `O_(2), SO_(2)`. Solution :Electrolysis of a solution of `Na_(2)SO_(4)` with PT (INERT) ELECTRODES gives `H_(2)` (at cathode) and `O_(2)` (at anode).

Discussion

21.	An aqueous solution of sodium acetate has pH greater than 7. Explain with equation.
Answer» Solution :Sodium ACETATE is a salt of a strong and a weak ACID which UNDERGOES hydrolysis to from strong alkaline (basic) solution. Hence the pH is GREATER than 7. `CH_(3)COONa+H_(2)OhArrCH_(3)COOH+nNaOH`

Discussion

22.	An aqueous solution of silver nitrate gives a white precipitate with
Answer» `C_(2)H_(5)CL` `CHCl_(3)` `HCL` `ICl_(3)` Answer :C

Discussion

23.	An aqueous solution of salt (P) gives white precipitate with barium chloride solution which is insoluble in dilute HCI and dilute HNO_(3). When ammonia (aq) is added to the aqueous solution of salt (P) blue precipitate is obtained which dissolves in excess ammonia producing deep blue colouration due to formation complex (Q). With KCN, (P) gives first a yellow precipitate which quickly decomposes to white precipitate along with liberating highly poisonous gas (R).(R) on hydrogenation produces (S) which gives yellowish orange coloured complex (T) with CoCI_(3). Which of the following options is correct with respect to P,Q,R,S and T?
Answer» P is `Ag_(2)SO_(4)'Q'` is `[Ag(NH_(3))_(2)]_(2)SO_(4)` S is a bidentate ligand and R is cyanogen R is `CH_(2)N_(2)` and P is `CuSO_($)` None of the above options is correct Solution :`P rarr CuSO_(4), Q rarr [Cu(NH_(3))_(4)] SO_(4), R rarr (CN)_(2)` `{:(S rarr,CH_(2)-NH_(2)),(,""\|),(,CH_(2)-NH_(2)):}` `T rarr[Co(en)_(3)]^(3+)` `Q rarr` Paramagnetic square planar `T rarr` Diamagnetic, octahedral

Discussion

24.	An aqueous solution of salt (P) gives white precipitate with barium chloride solution which is insoluble in dilute HCI and dilute HNO_(3). When ammonia (aq) is added to the aqueous solution of salt (P) blue precipitate is obtained which dissolves in excess ammonia producing deep blue colouration due to formation complex (Q). With KCN, (P) gives first a yellow precipitate which quickly decomposes to white precipitate along with liberating highly poisonous gas (R).(R) on hydrogenation produces (S) which gives yellowish orange coloured complex (T) with CoCI_(3). Which of the following options regarding complex Q and T is not correct?
Answer» Q is PARAMAGNETIC where as T is diamagnetic Q has a square planar GEOMETRY where as T has octahedral geometry When dissolved in water, Van't Hoff coefficient for Q is 2 and that of T is 4 (assuming 100% dissociation and monocations). Only ONE of the above statement is correct. Solution :`P rarr CuSO_(4), Q rarr [Cu(NH_(3))_(4)] SO_(4), R rarr (CN)_(2)` `{:(S rarr,CH_(2)-NH_(2)),(,""\|),(,CH_(2)-NH_(2)):}` `T rarr[Co(EN)_(3)]^(3+)` `Q rarr` Paramagnetic square planar `T rarr` Diamagnetic, octahedral

Discussion

25.	An aqueous solution of NH_(4)Cl is acidic. Give reason.
Answer» SOLUTION :Due to hydrolysis PRODUCE HCl, reaction `NH_(4)Cl+H_(2)Oto underset("Strong acid")(HCl)+underset("Weak base")(NH_(4)OH)`

Discussion

26.	An aqueous solution of metal ion M_(1) reacts separately with reagents Q and R in excess to give tetrahedral and square planar complexes, respectively. An aqueous solution of anotherr metal ion M_(2) always forms tetrahedral complex with these reagents. Aqueous solution of M_(2) on reaction with reagent S gives white precipitate which dissolves in excess of S. The reactions are summarized in the scheme given ahead. SCHEME: Tetrahedral overset(Q)underset("excess")larr M_(1)overset(R)underset("excess")rarr Square planar {:("Tetrahedral"overset(Q)underset("excess")larrM_(2)overset(R)underset("excess")rarr"Tetrahedral"),(""darrS."stoichiometric amount"),("""White ppt" overset(S)underset("excess")rarr."Precipitate dissolves"):} Reagent S is:
Answer» `K_(4)[Fe(CN)_(6)]` `Na_(2)HPO_(4)` `K_(2)CrO_(4)` `KOH` ANSWER :D

Discussion

27.	An aqueous solution of metal ion M_(1) reacts separately with reagents Q and R in excess to give tetrahedral and square planar complexes, respectively. An aqueous solution of anotherr metal ion M_(2) always forms tetrahedral complex with these reagents. Aqueous solution of M_(2) on reaction with reagent S gives white precipitate which dissolves in excess of S. The reactions are summarized in the scheme given ahead. SCHEME: Tetrahedral overset(Q)underset("excess")larr M_(1)overset(R)underset("excess")rarr Square planar {:("Tetrahedral"overset(Q)underset("excess")larrM_(2)overset(R)underset("excess")rarr"Tetrahedral"),(""darrS."stoichiometric amount"),("""White ppt" overset(S)underset("excess")rarr."Precipitate dissolves"):} M_(1),Q and R, respectively are:
Answer» `ZN^(2+),KCN` and `HCI` `Ni^(2+),HCI` and KCN `Cd^(2+),KCN` and HCI `CO^(2+),HCI` and KCN Answer :B

Discussion

28.	An aqueous solution of H_(2)O_(2) is purified by
Answer» Distillations Fractional distillation Steam distillation Distillation under reduced pressure Solution : An aqueous solution of `H_(2_(2)` is PURIFIED by distillation under reduced PRESURE.

Discussion

29.	The aqueous solution of glucose is 10% w/w of solution, the percentage of w/w of solvent is
Answer» 18 litres 9 litres 0.9 litres 1.8 litres Solution :`(w)/(v)xx100=10,1" mole"=180GM` `impliesV=(180xx100)/(10)mL=1.8L`

Discussion

30.	An aqueous solution of H_(2)O_(2) is labeled as 33.6 vol. The amount of H_(2)O_(2) present is 50ml of such an aqueous solution is
Answer» `5.1` GM `10.2` gm `3.4` gm `0.34` gm Answer :A

Discussion

31.	An aqueous solution of compound A gives ethane or electrolysis. The compound A is :
Answer» Ethyl ACETATE Sodium acetate Sodium propionate Sodium ethoxide. Solution :`UNDERSET("Sodium acetate")(CH_(3)COONa) overset("ELECTROLYSIS")to CH_(3)CH_(3)`

Discussion

32.	An aqueous solution of boric acid is found to be weakly acidic in nature. This acidic character arises due to the following reasons.
Answer» It is a protic acid which donates protons in aqueous solution. It is a LEWIS acid which abstracts `OH^(-)` from water and leaves `H^(+)` to make to solution acidic It gives metaboric acid when dissolved in water. It is prepared by reaction of borax with sulphuric acid hence it behaves as an acid. Solution :It REACTS with water to abstract `OH^(-)` ions and RELEASES `H_(3)O^(+)` ION making it acidic.

Discussion

33.	An aqueous solutionof boraxis (a) neutral , (b)amphoteric , (c ) basic, (d) acidic
Answer» Solution :BORAX is a salt of astrong base `(NAOH)`and a weak acid `(H_(3)BO_(3))`,THEREFORE, it is basic in NATURE, i.e, option (c ) is correct.

Discussion

34.	An aqueous solution of borax is
Answer» Neutral Amphoteric Basic Acidic Solution :c.Borax is a salt of STRONG base and WEAK acid `Na_(2)B_(4)O_(7)+7H_(2)Otounderset("base")underset("Strong")(2NaOH)+underset("acid")underset("Weak")(4B(OH)_(3))` THEREFORE, aqueous solution will be basic in nature.

Discussion

35.	An aqueous solution of borax is …….
Answer» neutral amphoteric BASIC ACIDIC ANSWER :C

Discussion

36.	An aqueous solution of aniline of concentration 0.24 M is prepared. What concentraton of sodium hydroxide is needed in this solution so that anilinium ion concentration remains at 1xx10^(-8) M? (K_(a) "for" C_(6)H_(5)NH_(3)^(+)=2.4xx10^(-6)M)
Answer» Solution :In aqueous solution, ANILINE is hydrolysed as `C_(6)H_(5)NH_(2)+ H_(2)O hArr C_(6)H_(5)overset(+)N H_(3)+OH^(-)` When NAOH is added, hydrolysis will be supressed so that in the final solution, `[C_(6)H_(5) overset(+)NH_(3)]=10^(-8)M` (Given) In conc. of NaOH added is x mol `L^(-1)`, then at EQUILIBRIUM `[C_(6)H_(5)NH_(2)]=0.24-10^(-8) ~= 0.24` `[C_(6)H_(5)overset(+)NH_(3)]=10^(-8)M` (Given) `[OH^(-)]=10^(-8)+x ~= x M` Hydrolysis constant, `K_(h) = ([C_(6)H_(5)overset(+)H_(3)][OH^(-)])/([C_(6)H_(5)NH_(2)])` ...(i) Further, we are given `C_(6)H_(5)overset(N)H_(3) hArr C_(6)H_(5)NH_(2)+H^(+)` `K_(a) = ([C_(6)H_(5)NH_(2)][H^(+)])/([C_(6)H_(5)overset(N)H_(3)])` ...(ii) Also `[H^(+)][OH^(-)]=K_(w)`...(iii) Combining eqns. (i), (ii) and (iii) `k_(h)=(K_(w))/(K_(a))=(10^(-14))/(2.4xx10^(-6))=(10^(-8))/(2.4)` Substituting the values in eqn. (i), we get, `(10^(-8))/(2.4)=(10^(-8)xx x)/(0.24)` which gives `x=10^(-2)M`

Discussion

37.	An aqueous solution of an inorganic compound (X) shows the following reactions : (i) It decolourises an acidifed KMnO_(4) solution accomopained by evolution of oxygen . (ii) It libirates iodine from an acidified potassium iodide solution . (iii) It gives brown precipitate with an alkaline KMnO_(4) solution with the evolution of oxygen. (iv) It removes black stains from oil paintings. Identify (X) and write equations for the reactions involved.
Answer» Solution :(i) Compound (X) acts as a reducing AGENT both in acidic as well as in the BASIC medium because it decolourises an acidified solution of `KMnO_(4)` with evolution of `O_(2)` and produces a brown ppt. (probably of `MnO_(2)`) with evolution of `O_(2)` in the basic medium. (II) Compound (X) also acts as an oxidising agent since it liberates `I_(2)` from an acidified solution of KI. All these reactions of characteristic of `H_(2)O_(2)`. Therefore , compound (X) is `H_(2)O_(2)` (iii) Further `H_(2)O_(2)` is known to remove black stains from old oil paintins DUE to oxidation of black PbS to with `PbSO_(4)`. If compound (X) is `H_(2)O_(2)`, then all the reactions involved in this problem may be explained as FOLLOWS : `(i) 2KMnO_(4) + 3H_(2)SO_(4) + 5H_(2)O_(2) to 2K_(2)SO_(4) + 2MnSO_(4) = 3H_(2)O + 5O_(2)` `(ii) 2KMnO_(4) + 3H_(2)O_(2) to underset("Brown ppt.")(2MnO_(2))+ 2KOH + 2H_(2)O+ 3O_(2)` `(iii) 2KI + H_(2)SO_(4) + H_(2)O_(2)to K_(2)SO_(4) + I_(2) + 2H_(2)O` `(iv) underset("Black")(PbS) + 4H_(2)O_(2) to underset("White")(PbSO_(4))+4H_(2)O`

Discussion

38.	An aqueous solution of an inorganic compound (X) shows the following reactions : (i) It decolourises an acidified KMnO_4 solution accompanied with evolution of oxygen gas. (ii) It liberates iodine from acidified potassium iodide solution. (iii) It gives brown precipitate with alkaline KMnO_4 solution with evolution of oxygen gas. (iv) It removes black stains from old oil paintings. Identify (X) and give chemical reactions for steps (i) to (iv).
Answer» Solution :Since X REMOVES black stains from old oil paintings, it is HYDROGEN peroxide `H_2 O_2` `(i) underset((X))(5H_2 O_2) + 2K MnO_4 + 3H_2 SO_4 to K_2 SO_4 + 2MnSO_4 + 8H_2 SO_4 + 5O_2` (ii) `H_2 O_2 + 2KI + H_2 SO_4 to I_2 + K_2 SO_4 + 2H_2 O` (iii) `underset((X))(3H_2 O_2) + 2KMnO_4) to underset("Brown PPT")(2MnO_2 +2KOH + 3O_2 + 2H_2 O` (iv) `4H_2 O_2 + underset("(black)")(PBS) to underset("white")(PbSO_4) + 4H_2 O`

Discussion

39.	An aqueous solution of alum is
Answer» ACIDIC Basic NEUTRAL Amphoteric Solution : An aqueous solution of ALUM is acidic due to CATIONIC hydrolysis

Discussion

40.	An aqueous solution of a substance gives a white precipitate on treatment with NaCI solution, which dissolves on heating. When H_(2)S gas is passed through it's hot acidic solution, a black precipitate is obtained. The cations which are not associated with this test are:
Answer» `Mg^(2+)` `AG^(+)` `Hg_(2)^(2+)` `PB^(2+)` ANSWER :A::B::C

Discussion

41.	An aqueous solution of a mixture of two inorganic salts when treated with dilute HCl, gave a precipitate (P) and a filtrate (Q). The precipitate (P) was found to dissolve in hot water. The filtrate (Q) remained unchanged, when treated with H_(2)S in a dilute mineral acid medium. However, it gave a green precipitate (R) in an ammoniacal medical. The precipitate (R) gave a coloured solution (S), when treated with H_(2)O_(2) in an aqueous NaOH medium. Answer Question 62 and 63 The coloured solution (S) contains
Answer» `Fe(SO_(4))_(3)` `CuSO_(4)` `ZnSO_(4)` `Na_(2)CrO_(4)` Solution :The coloured solution (S) is `Na_(2)CrO_(4)` The AVAILABLE data suggests that the mixture contains `Pb^(2+)` and `Cr^(3+)` ions. The series of reactions involved are :

Discussion

42.	An aqueous solution of a mixture of two inorganic salts when treated with dilute HCl, gave a precipitate (P) and a filtrate (Q). The precipitate (P) was found to dissolve in hot water. The filtrate (Q) remained unchanged, when treated with H_(2)S in a dilute mineral acid medium. However, it gave a green precipitate (R) in an ammoniacal medical. The precipitate (R) gave a coloured solution (S), when treated with H_(2)O_(2) in an aqueous NaOH medium. Answer Question 62 and 63 The precipitate P contains
Answer» <P>`Pb^(2+)` `Hg_(2)^(2+)` `AG^(+)` `Hg^(2+)` SOLUTION :The precipitate (P) contains `Pb^(2+)` IONS.

Discussion

43.	An aqueous solution of a mixture contains Br^(-) and I^(-) ions. On passing Cl_(2) gas and adding CHCl_(3), then organic layer will acquire :
Answer» VIOLET colour reddish brown colour colourless blue colour Solution :Violet colour will APPEAR in `CS_(2)` LAYER. It is DUE to `I^(-)` ions. The violet colour masks the ORANGE colour of `Br^(-)` ions.

Discussion

44.	An aqueous solution of a metal bromide MBr_(2) (0.05 M) is saturated with H_(2)S. What is the minimum pH at which MS will be precipitated ? (K_(sp) "for MS" = 6.0 xx 10^(-21), "concentration of saturated " H_(2)S=0.1M, K_(1)=10^(-7) and K_(2)=1.3xx10^(-13) "for " H_(2)S).
Answer» Solution :`[M^(2+)]=[MBr_(2)]=0.05 M ` For the precipitation of MS, minimum `[S^(2-)]` can be calculated from `[S^(2-)][M^(2+)]=K_(SP)` i.e., `[0.05][S^(2-)]=6.0xx10^(-21) or [S^(2-)]=1.2xx10^(-19)` `S^(2-)` IONS are obtained from following dissociations `H_(2)S overset(K_(1)) hArr H^(+)+HS^(-)` `HS^(-) overset(K_(2))hArr H^(+)+S^(2-)` `K_(1) = ([H^(+)][HS^(-)])/([H_(2)S]),K_(2) = ([H^(+)][S^(2-)])/([HS^(-)])` `:. K_(1)K_(2)=([H^(+)]^(2)[S^(2-)])/([H_(2)S])` `10^(-7)xx1.3xx10^(-13)=([H^(+)]^(2)[1.2xx10^(-19)])/((0.1)) or [H^(2)]^(2)=(1.3xx10^(-20)xx10^(-1))/(1.2xx10^(-19))=1.083xx10^(-2)` or `[H^(+)]=1.041xx10^(-1)=0.1041 M` `:. pH = - log (0.1041)=0.9826`

Discussion

45.	An aqueous solution of 6.3 g of oxalic acid dihydrate is made up to 250 mL. The volume of 0.1 N NaOH required to completely neutralise 10 mL of this solution is :
Answer» 40 mL 20 mL 10 mL 4 mL Solution :N//A

Discussion

46.	An aqueous solution of 2% nonvolatile solute exerts a pressure of 1. 004 bar at the boiling point of the solvent. What is the molar mass of the solute when P_(A) ^(@) is 1.013 bar ?
Answer» Solution :VAPOUR pressure of pure WATER at the boiling point. `(P^(0)) =1 atm = 1.013` BAR Vapour pressure of solution `P _(S) = 1. 004` bar `M_(1) = 18 g mol ^(-1)` `M _(2) ` = ? Mass of solute `= W_(2) = 2g` Mass of solution = 100 g Mass of solvent `W_(1) = 98 g` Applying Ranoult.s law for dilute solution `(P ^(0) -P_(S))/(P ^(0)) = (n_(2))/(n _(1) + n _(2)) = (n_(2))/( n _(1))= ((W _(2))/( M _(2)))/( (W _(1))/( M _(2)))` `(P ^(0) -P_(S))/(P ^(0))= (W_(2))/(M _(2)) xx (M_(1))/(W _(1))` `(1.013-1,004)/(1.013) = (W_(2))/(M _(2)) xx (18 mol ^(-1))/(98G) (or)` `M _(2) = (2 xx 18 xx 1. 103)/(98 xx 0.009) = 41.35g mol ^(-1)`

Discussion

47.	An aqueous solution of 0.10 g KIO_(3) was treated with an excess of KI solution the solution was acidified with HCI the liberated I_(2) consumed 45.0 mL ofthisuplhate solutoin to decolourise the blue starch iodine complex calculate the molarity of sodium thiossuphate solution
Answer» SOLUTION :The reaction involved are `2IO_(3)^(-)+12 H^(+)+10 I^(-) rarr 6 I_(2)+6 H_(2)O` `2S_(2)O_(3)^(2-)+I_(2)rarrS_(4)O_(6)^(2-)+2I^(-)]xx6` `2IO_(3)^(-)+12 H^(+)+12 H^(+)+12 S_(2)O_(3)^(2-)rarr6S_(4)O_(6)^(2-)+2 I^(-)+6H_(2)O` Now of moles of `KIO_(3)=(0.1)/(214)` Now 2 moles of `KIO_(3)` react with `Na_(2)S_(2)_(3)`=12 moles `therefore (0.1)/(214)` mole of `KIO_(3)` will react with `Na_(2)S_(2)O_(3)=12/2xx(0.1)/(214)` mole Now `12/2xx(0.1)/(214)` mole of `Na_(2)S_(2)O_(3)` s present in 45 ML of the soluton `therefore` MOLARITY of `Na_(2)S_(2)O_(3)` solution =`12/2xx(0.1)/(214xx1000/45=0.0623 M`

Discussion

48.	An aqueous solution is made by dissolving glucose (C_(6)H_(12)O_(6)) and urea (NH_(2)CONH_(2)) in water. Moleratio of glucose and water is 1:10 . If the masses of glucose and urea are in 3:1 ratio, then correct statement(s) regarding the solution is/are:
Answer» The MOLE fraction of glucose in the solution is `(1)/(11)` The mole fraction of urea in the solution is `(1)/(12)` MOLALITY of glucose in the solution is `(25)/(6)` Molality of urea in the solution is `(50)/(9)` ANSWER :B::D

Discussion

49.	An aqueous solution is 1 molal in KI. Which change will cause the vapour pressure of the solution to increase ?
Answer» ADDITION of NaCl Assition of `Na_(2)SO_(4)` Addition of 1 MOLAL KI Addition of water Answer :D

Discussion

50.	An aqueous solution contains an unknown concentration of Ba^(2+). When 50 ml of a 1M solution of Na_(2)SO_(4) is added. BaSO_(4)just begins to precipitate. The final volume is 500ml. The solubility product ofBaSO_(4) " is " 1 xx 10^(-10)Find the original concentration.
Answer» Solution :`K_("SP") = [Ba^(2+)][SO_(4)^(2-)] = [Ba^(2+)][(50xx1)/500] = 10^(-9) xx 500 ` `Ba^(2+) = 10^(-9) M` ` 10^(-9) xx 500 = 450 xx M "" :. M = 1.11 xx 10^(-9) M `

Discussion

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An atom has a mass number of 23 and atomic number 11. The number of protons are ______

An atom of an element 'A' has three electrons in its outermost shell and that of 'B' has six electrons in the outrer most shell. The formula of the compound formed between these two elements is

An atom A belongs to IIA group and another atm B belongs to VA group. The fomula of the compound formed is

An atom differs from its ion in

An athelete is given 100 g of glucose (C_(6)H_(12)O_(6)) of energy equivalent to 1560 kJ. He utilizes 50% of this gained energy in the event. In order to avoid storage of energy in body , the weight of water he would need to perspire is : (The enthalpy of evaporation of water is 44 kJ//mole)

An astronaut receives the energy required in his body by the combustion of 34gm of sucrose per hour. How much oxygen he has to carry along with him for his energy requirement in a day?

An astronaut receives the energy required in his body by the combustion of 34g of sucrose per hour. How much oxygen he has to carry along with him for his energy requirement in a day?

An aromatic molecule will

An aromatic compound having C_(7)H_(8)O as the molecular formula has.................isomers.

An aromatic compound has molecular formula C_(7)H_(8)O. The number of phenolic isomers for this compound is

An aqueous solution of sucrose, C_(12)H_(22)O_(11), containing 23.2g/L has an osmotic pressure of 2.38 atmosphere at 17^(@)C, For an aqueous solution of glucose, C_(6)H_(12)O_(6), to be isotonic with this solution, it would have :

An aqueous solution of sodium sulphate is electrolysed using inert electrodes. The products at the cathode and anode are respectively

An aqueous solution of sodium acetate has pH greater than 7. Explain with equation.

An aqueous solution of silver nitrate gives a white precipitate with

An aqueous solution of NH_(4)Cl is acidic. Give reason.

An aqueous solution of H_(2)O_(2) is purified by

The aqueous solution of glucose is 10% w/w of solution, the percentage of w/w of solvent is

An aqueous solution of H_(2)O_(2) is labeled as 33.6 vol. The amount of H_(2)O_(2) present is 50ml of such an aqueous solution is

An aqueous solution of compound A gives ethane or electrolysis. The compound A is :

An aqueous solution of boric acid is found to be weakly acidic in nature. This acidic character arises due to the following reasons.

An aqueous solutionof boraxis (a) neutral , (b)amphoteric , (c ) basic, (d) acidic

An aqueous solution of borax is

An aqueous solution of borax is …….

An aqueous solution of aniline of concentration 0.24 M is prepared. What concentraton of sodium hydroxide is needed in this solution so that anilinium ion concentration remains at 1xx10^(-8) M? (K_(a) "for" C_(6)H_(5)NH_(3)^(+)=2.4xx10^(-6)M)

An aqueous solution of alum is

An aqueous solution of a substance gives a white precipitate on treatment with NaCI solution, which dissolves on heating. When H_(2)S gas is passed through it's hot acidic solution, a black precipitate is obtained. The cations which are not associated with this test are:

An aqueous solution of a mixture contains Br^(-) and I^(-) ions. On passing Cl_(2) gas and adding CHCl_(3), then organic layer will acquire :

An aqueous solution of a metal bromide MBr_(2) (0.05 M) is saturated with H_(2)S. What is the minimum pH at which MS will be precipitated ? (K_(sp) "for MS" = 6.0 xx 10^(-21), "concentration of saturated " H_(2)S=0.1M, K_(1)=10^(-7) and K_(2)=1.3xx10^(-13) "for " H_(2)S).

An aqueous solution of 6.3 g of oxalic acid dihydrate is made up to 250 mL. The volume of 0.1 N NaOH required to completely neutralise 10 mL of this solution is :

An aqueous solution of 2% nonvolatile solute exerts a pressure of 1. 004 bar at the boiling point of the solvent. What is the molar mass of the solute when P_(A) ^(@) is 1.013 bar ?

An aqueous solution of 0.10 g KIO_(3) was treated with an excess of KI solution the solution was acidified with HCI the liberated I_(2) consumed 45.0 mL ofthisuplhate solutoin to decolourise the blue starch iodine complex calculate the molarity of sodium thiossuphate solution

An aqueous solution is made by dissolving glucose (C_(6)H_(12)O_(6)) and urea (NH_(2)CONH_(2)) in water. Moleratio of glucose and water is 1:10 . If the masses of glucose and urea are in 3:1 ratio, then correct statement(s) regarding the solution is/are:

An aqueous solution is 1 molal in KI. Which change will cause the vapour pressure of the solution to increase ?

An aqueous solution contains an unknown concentration of Ba^(2+). When 50 ml of a 1M solution of Na_(2)SO_(4) is added. BaSO_(4)just begins to precipitate. The final volume is 500ml. The solubility product ofBaSO_(4) " is " 1 xx 10^(-10)Find the original concentration.