52671 + Interview Questions in Chemistry in Class 11 Page 1011 InterviewSolution

50501.	A colourless mixture of two salts (A) and (B) excess is soluble in H_(2)O. Separately (A) turns blue litmus red and (B) turns red litmus blue. (A) given white precipitate with (B), which dissolves in excess of (B) forming (C). (A) when placed in moist air gives fumes and can form dimer. (A) gives white precipitate with NH_(4)CI and NH_(4)OH soluble in (B).(A) also gives white precipitate with AgNO_(3) soluble in NH_(4)OH. Colourless mixture contains:
Answer» `ZnCI_(2),NaOH` `AICI_(3),NACI` `AICI_(3),NaOH` `CrCI_(3),NaOH` Solution :`(A) rarr AICI`, (B) `rarr NaOH, AI^(3+) +H_(2)O HARR AI(OH)^(2+) +H^(+)`

Discussion

50502.	A colourless liquid, at room temperature reacts with soda lime to form sodium salt of carboxylic acid and ammonia gas. The liquid is
Answer» Propanamide Propanoic ACID Formamide Methyl Ethanoate Solution :Since in the REACTION sodium salt of fatty acid is formed it must be an acid or some acid derivative. Further since `NH_(3)` gas is alos evolved hence it must be an amide. Moreover, at room while all other AMIDES are COLOURLESS CRYSTALLINE solids

Discussion

50503.	A colourless liquid A contains H and O elements only. It decomposes slowly on exposusre to light. It is stabilized by mixing urea to store in the presence of light. (i) Suggest possible structrue of A. (ii) Write chemical equatioins of its decomposition reaction in light.
Answer» Answer :The liquid A is hydrogen pexoxide `(H_(2)O_(2))` `(##SPH_BSR_CHE_QB_XI_MQP_01_E01_023_S01##)` `2H_(2)O_(2)OVERSET("LIGHT")(to)2H_(2)O+O_(2)`

Discussion

50504.	A colourless liquid 'A' contains H and O elements only. It decomposes slowly on exposure to light. Is stabilised by mixing urea to store in the presence of light. (i) Suggest possible structure of A. (ii) Write chemical equations for its decomposition reaction in light.
Answer» Solution :SINCE a colourless liquid 'A' contains only H and O and decomposes slowly on EXPOSURE to LIGHT but is stabilised by addition of urea, therefore , liquid A may be HYDROGEN peroxide. (i) `2H_(2)O_(2) OVERSET(hv)to 2H_(2)O+ O_(2)`.

Discussion

50505.	A colourless liquid .A. contains H and o elements only. It decomposes slowly on exposure to light. It is stabilised by mixing urea to store in the presence of light. (i) Suggest possible structure of A. (ii) Write chemical equations for decomposition reaction in light.
Answer» SOLUTION :(i) Since, a colourless liquid .A. contains only hydrogen and oxygen and decomposes slowly on EXPOSURE to light but is stabilised by addition of urea, therefore, liquid A may be `H_2O_2`.The STRUCTURE of `H_2O_2`is (ii)`2H_2O_2 underset"Sunlight"overset"HV" to 2H_2O+O_2`

Discussion

50506.	A colourless inorganic salt (A) decomposes completely at about 250^(@)C to give only two products, (B) and (C), leaving no residue. The oxide (C) is a liquid at room temperature and neutral to moist litmus paper while the gas (B) is a neutral oxide. White phosphours burns in excess of (B) to produce a strong white dehydrating agent. Write balanced equations for the reactions involved in the above process.
Answer» Solution :(i) Since a colourless inorganic salt (A) on HEATING to `250^(@)C` DECOMPOSES to form twooxides (B) and (C) leaving no residue, therefore, compound (A) must be ammonium nitrate `(NH_(4)NO_(3))`. `underset((A))(NH_(4)NO_(3))overset(250^(@)C)tounderset((B))(N_(2)O)+underset((C))(2H_(2)O)` (ii) The fact that inorganic salt (A) is actually ammonium nitrate is confirmed by the observation that oxide (C), i.e., `H_(2)O` is a liquid at room temperature. (iii) If the oxide (C) is `H_(2)O` then other neutral oxide (B) must be nitrous oxide, `N_(2)O`. (iv) The fact that the neutral oxide (B) is actually `N_(2)O` is confirmed by the observation that white phosphorus burns in `N_(2)O` to form phosphorus pentoxide which is a strong dehydrating agent. `underset("Nitrous oxide (B)")(10N_(2)O)+P_(4)tounderset("Phosphorus pentoxide")(P_(4)O_(10))+10N_(2)` Thus, inorganic salt (A) is ammonium nitrate `(NH_(4)NO_(3))`, (B) is nitrous oxide `(N_(2)O)` and (C) is water `(H_(2)O)`.

Discussion

50507.	A colourless gas which burns with blue flame and reduces CuO to Cu is
Answer» `N_(2)` `CO` `CO_(2)` `NO_(2)` ANSWER :B

Discussion

50508.	A colourless gas obtain by the electrolysis of NaCl Nelson's cell is made to combine with an element X. The resulting compound has low mellting pt. and boiling pt. It can also act as weak reducing pt. and boiling pt. It can also act as weak reducing agent. The element X forms oxides and hydroxides of the form X_(2)O_(3) and X(OH)_(3). X does not react with HCl. The resulting compound is
Answer» `AlCl_(3)` `B_(2)H_(6)` `BCl_(3)` `Ga_(2)Cl_(6)`. Solution :Chlorine from Nelson cell forms `BCl_(3)` with boron.

Discussion

50509.	A coloured solution known to contain two metal ions of different groups, was treated with excess cold sodium hydroxide solution. When filtered a whitish solid, slowly changing to brown, was retained on the filter paper and a colourless solution collected as the filtrate. Drop wise adition of hydrochloric acid to the filtrate produced a white precipitate which dissolved in excess acid. Treatment of the residue from the filter paper with a strong oxidiser, PbO_(2) and concentratedHNO_(3) on boiling produced a reddish-violet (purple) solution. Reddish-violet (purple) solution is decolourised by:
Answer» both `SO_(3)^(2-),FE^(2+)` both `SO_(4)^(2-),Fe^(3+)` both `NO_(3)^(-),Fe^(2+)` both `H_(2)O_(2),HCO_(3)^(2-)` Answer :A

Discussion

50510.	A coloured solution known to contain two metal ions of different groups, was treated with excess cold sodium hydroxide solution. When filtered a whitish solid, slowly changing to brown, was retained on the filter paper and a colourless solution collected as the filtrate. Drop wise adition of hydrochloric acid to the filtrate produced a white precipitate which dissolved in excess acid. Treatment of the residue from the filter paper with a strong oxidiser, PbO_(2) and concentratedHNO_(3) on boiling produced a reddish-violet (purple) solution. Reddish-violet solution obtained by oxidation is of:
Answer» `ZnO_(2)^(2-)` `MnO_(4)^(2-)` `MnO_(4)^(-)` `MnO_(2)` Answer :C

Discussion

50511.	A coloured solution known to contain two metal ions of different groups, was treated with excess cold sodium hydroxide solution. When filtered a whitish solid, slowly changing to brown, was retained on the filter paper and a colourless solution collected as the filtrate. Drop wise adition of hydrochloric acid to the filtrate produced a white precipitate which dissolved in excess acid. Treatment of the residue from the filter paper with a strong oxidiser, PbO_(2) and concentratedHNO_(3) on boiling produced a reddish-violet (purple) solution. White solid changing to brown is due to formation of:
Answer» `Mn(OH)_(2)` `MgO` `AI(OH)_(3)` `MNO(OH)_(2)` ANSWER :D

Discussion

50512.	A coloured solution known to contain two metal ions of different groups, was treated with excess cold sodium hydroxide solution. When filtered a whitish solid, slowly changing to brown, was retained on the filter paper and a colourless solution collected as the filtrate. Drop wise adition of hydrochloric acid to the filtrate produced a white precipitate which dissolved in excess acid. Treatment of the residue from the filter paper with a strong oxidiser, PbO_(2) and concentratedHNO_(3) on boiling produced a reddish-violet (purple) solution. Filtrate obtained after separation of white solid contains:
Answer» `[AI(OH)_(4)]^(-)` `AI_(2)O_(3)` `MNO` `Na_(2)MnO_(2)` Answer :A

Discussion

50513.	A coloured solution known to contain two metal ions of different groups, was treated with excess cold sodium hydroxide solution. When filtered a whitish solid, slowly changing to brown, was retained on the filter paper and a colourless solution collected as the filtrate. Drop wise adition of hydrochloric acid to the filtrate produced a white precipitate which dissolved in excess acid. Treatment of the residue from the filter paper with a strong oxidiser, PbO_(2) and concentratedHNO_(3) on boiling produced a reddish-violet (purple) solution. Indicate any pairs of ions which on testing as above leads to the observed changes.
Answer» `AI^(3+)` and `MN^(2+)` ions `MG^(2+)` and `ZN^(2+)` ions `Mn^(2+)` and `Mg^(2+)` ions `Zn^(2+)` and `Mn^(2+)` ions Answer :A

Discussion

50514.	A coloured salt of cobalt is subjected to borax bead test. The transparent borax bead turns blue. From the given reaction, identify the one which does not take place during the process
Answer» `4NaBO_(2) + CO_(2) rarr Na_(2)B_(4)O_(7) + Na_(2)CO_(3)` `Na_(2)B_(4)O_(7) rarr 2NaBO_(2) + B_(2)O_(3)` `Na_(2)[B_(4)O_(5)(OH)_(4)].8H_(2)O rarr Na_(2)B_(4)O_(7) + 10H_(2)O` `CoO + B_(2)O_(3) rarr Co(BO_(2))_(2)` ANSWER :A

Discussion

50515.	A colloidal solution of Na in ether is
Answer» golden YELLOW in COLOUR blue in colour colourless violet in colour. SOLUTION :A colloidal solution of NA in ETHER is violet coloured.

Discussion

50516.	A colloidal solution of gold in water is
Answer» red in colour blue in colour golden spangles all the three. Solution :Colour of a COLLOIDAL solution depends UPON particle size. As the particle size INCREASE, the colour of gold sol changes from red to blue and finally to golden spangles. At this stage, it turns into a suspension.

Discussion

50517.	A colloidal solution is subjected to an electrical field. The particles move towards anode. The coagulation of same sol is studied using NaCl, BaCl_(2) and AlCl_(3)solution. Their coagulating power should be
Answer» `NaCl GT BaCl_(2) gt AlCl_(3)` `BaCl_(2) gt AlCl_(3) gt NaCl` `AlCl_(3) gt BaCl_(2) gt NaCl` `BaCl_(2) gt NaCl gt AlCl_(3)` Answer :C

Discussion

50518.	(a) Colloidal sol of Fe(OH)_3 formed by peptization carries positive chrage. (r) During the formation of positively charged colloidal particles of Fe(OH)_3 the electons are lost by the colloidal particles of Fe(OH)_3.
Answer» IF both (A) and (R) are CORRECT and (r) is the correct explanation for (a). If both (a) and (r) are correct but (r) is not the correct explanation for (a). IF (a) is correct but (r) is INCORRECT. If (a) is incorrect but (r) is correct. Answer :C

Discussion

50519.	(A): COD of water is detennined by oxidising the organic matter with acidified (50% H_2SO_4) potassium dichromate solution (R) Greater the COD value of water greater is its pollution
Answer» Both (A) and (R) are TRUE and (R) is the CORRECT explanation of (A) Both (A) and (R) are true and (R) is not the correct explanation of (A) (A) is true but (R) is false (A) is false but (R) is true ANSWER :B

Discussion

50520.	(A): CO pollution is very high from 9AM to 10 AM in Urban areas (R): Almost 80% CO is released from Automobiles
Answer» Both (A) and (R) are true and (R) is the CORRECT explanation'of (A) Both (A) and (R) are true and (R) is not the correct explanation of (A) (A) is true but (R) is false (A) is false but (R) is true SOLUTION :Both (A) and (R) are true and (R) is the correct explanation.of (A)

Discussion

50521.	A closed vessel contains equal number of oxygen and hydrogen molecules at a total pressure of 740 mm. If oxygen is removed from the system, the pressure: 1)becomes half of 740 mm2)becomes 1/3 rd of 740 mm3)becomes double of 740 mm4)remains unchanged.
Answer» BECOMES HALF of 740 mm becomes `1/3` RD of 740 mm becomes double of 740 mm remains unchanged. Solution :becomes half of 740 mm

Discussion

50522.	A closed steel Mask contains hot tea. What type of system is this?
Answer» SOLUTION :The system is a closed system. This is because HEAT transfers from the steel walls into the SURROUNDINGS,but MATTER is not transfered.

Discussion

50523.	A closed bulb cotains 0.01 mole of inert helium gas and a sample of solid white NH_(4)CI The pressure of the he is measured at 27^(@)C and is found to be 114 mm Hg The bulb is then heated to 327^(@)C All the NH_(4)CI decomposes according to the equation NH_(4)CI_((s))rarrNH_(3_(g)) +HCI_((g)) The final total pressure in the bulb after complete decomposition of solid is 908mm Hg Assume all the gases are ideal (a) What is the partial pressure of HCI_((g)) in the bulb at 327^(@)C when reaction is complete (b) How many grams of NH_(4)CI_((s)) were in the bulb at 27^(@)C ? .
Answer» ANSWER :0.447 ATM, 0.797 G

Discussion

50524.	A clear solution which is again converted into colloidal solution, the process is called
Answer» Peptization Electro addition Electrophoresis None of these Answer :D

Discussion

50525.	(a) Classify the following as pure substances and mixtures. (b)Separate the pure substances into elements and compounds and divide the mixtures into homogeneous and heterogeneous. (i) air (ii) milk (iii) graphite (iv) diamond (v) gasoline (vi) tap water (vii) distilled water(viii) oxygen (ix) one rupee-coin(x) 22 carat gold (xi) steel (xii) iron (xiii) sodium chloride(xiv) iodised table salt (xv) wood (xvi) cloud
Answer» Solution :(i) Air : MIXTURE, HOMOGENEOUS. (ii) Milk : mixture, heterogeneous (iii) Graphite : pure substance, element carbon (iv) Diamond : pure substance, element carbon (v) Gasoline : mixture, homogeneous (vi) Tap water : mixture, heterogeneous (vii) Distilled water : pure substance, COMPOUND (viii) Oxygen : pure substance, element (ix) One RUPEE coin : mixture, homogeneous (x) 22 carat gold : mixture, homogeneous (xi) Steel : mixture, homogeneous (xii) Iron : pure substance, element (xiii) Sodium chloride : pure substance, compound (xiv) Iodised table salt: mixture, heterogeneous (xv) Wood : pure substance, compound (xvi) CLOUD : mixture, heterogeneous.

Discussion

50526.	(a) Classify followingoxides as neutral, acidic, basic oramphoteric CO, B_(2)O_(3), SiO_(2), CO_(2), Al_(2)O_(3), PbO_(2), Tl_(2)O_(3) (b) Write suitablechemcial equationsto show their nature.
Answer» Solution :(a) Neutral oxides : CO : Acidic oxides : `B_(2)O_(3), SiO_(2), CO_(2)` Amphoteric oxides : `Al_(2)O_(3), PbO_(2)` Basicoxide : `Tl_(2)O_(3)` (b) (i) Being acidic `B_(2)O_(3), SiO_(2)` and `CO_(2)` react with ALKALIS to form salts. `UNDERSET("ANHYDRIDE")underset("Boric")(B_(2)O_(3)) + 2NaOH rarr underset("Sod. metaborate")(2NaBO_(2) + H_(2)O) , underset("Silica")(SiO_(2))+2NaOH overset(Delta)rarrunderset(" Sod. silicates ")(Na_(2)SiO_(3))+H_(2)O` `underset(" Carbon dioxide ")(CO_(2)) + 2NaOH rarr underset(" Sod. carbonate ")(Na_(2)CO) + H_(2)O` (ii) Being amphoteric, `Al_(2)O_(3)` and `PbO_(2)` reactwith bothacidsand bases. `underset("Alumina")(Al_(2)O_(3)) + 2NaOHoverset("Fuse")rarr underset(" Sod. meta-aluminate ")(NaAlO_(2)) + H_(2)O, Al_(2)O_(3) + 3H_(2)SO_(4) rarr Al_(2)(SO_(4))_(3) + 3H_(2)O` `underset(" Lead dioxide ")(PbO_(2)) + 2NaOH rarr underset(" Sod. plumbate ")(Na_(2)PbO_(3)) + H_(2)O , 2PbO_(2) + 2H_(2)SO_(4) rarr 2PbSO_(4) +2H_(2)O + O_(2)` (III) Beingbasic, `Tl_(2)O_(3)` dissolvesin acids. `Tl_(2)O_(3) + 6 HCl rarr 2TlCl_(3) + 3H_(2)O`.

Discussion

50527.	A chlorocompound (A) on reduction with Zn-Cu and ethanol gives the hydrocarbon (B) with five carbon atoms. When (A) is dissolved in dry ether and treated with sodium metal it gave 2,2,5,5,-tetramethylhexane. The treatment of A as A overset(alc. KCN)to C The reation of A with aq. KOH will preferably favour
Answer» `S_(N)1` MECHANISM `S_(N)2` mechanism `E_(1)` mechanism `E_(2)` mechanism Answer :A

Discussion

50528.	A chlorocompound (A) on reduction with Zn-Cu and ethanol gives the hydrocarbon (B) with five carbon atoms. When (A) is dissolved in dry ether and treated with sodium metal it gave 2,2,5,5,-tetramethylhexane. The treatment of A as A overset(alc. KCN)to C The reaction of C with Na, C_(2)H_(5)OH is called
Answer» GILMAN reaction Mendius reaction Grooves process Swart's reaction Answer :B

Discussion

50529.	A chlorocompound (A) on reduction with Zn-Cu and ethanol gives the hydrocarbon (B) with five carbon atoms. When (A) is dissolved in dry ether and treated with sodium metal it gave 2,2,5,5,-tetramethylhexane. The treatment of A as A overset(alc. KCN)to C The reaction of C with Na, C_(2)H_(5)OH gives
Answer» `(CH_(3))_(3)C CH_(2)CONH_(2)` `(CH_(3))_(3)CNH_(2)` `(CH_(3))_(3)C CH_(2)NH_(2)` `(CH_(3))_(2)CHCH_(2)NH_(2)` Answer :C

Discussion

50530.	A chlorocompound (A) on reduction with Zn-Cu and ethanol gives the hydrocarbon (B) with five carbon atoms. When (A) is dissolved in dry ether and treated with sodium metal it gave 2,2,5,5,-tetramethylhexane. The treatment of A as A overset(alc. KCN)to C The compound A is
Answer» 1-chloro-2, 2-dimethyl propane 1-chloro-2, 2-dimethyl butane 1-chloro-2-methyl butane 2-chloro-2-methyl butane Answer :A

Discussion

50531.	A chloro compound with M.F C_3H_3Cl shows the following properties (i) Decolourized bromine in C Cl_4 , (ii)Absorbed hydrogen catalytically, (iii)Gave a precipitate with ammoniacal cuprous chloride solution. Deduce the structure of the chloro compound.
Answer» Solution :(i)Since compound (A) absorbs hydrogen catalytically and decolourizes bromine in `C Cl_4`, it MUST be an unsaturated compound. (II)Since Compound (A) gives a precipitate with ammoniacal CUPROUS chloride, it must be a terminal alkyne. The only terminal alkyne with molecular FORMULA `underset"3-Chloro-1-propyne"(Cl-CH_2-C-=CH)` Step 1.To explain the reactions INVOLVED in the question (i)`underset"3-Chloro-1-propyne(A)"(Cl-CH_2-C-=CH)+ 2Br_2 overset(C Cl_4)to underset"1,1,2,2-Tetrabromo-3-chloropropane"(Cl-CH_2-CBr_2-CHBr_2)` (ii)`Cl-CH_2-C-=CH+2H_2 overset"Catalyst"to underset"1-Chloropropane"(Cl-CH_2-CH_2-CH_3)` (iii)`ClCH_2C-=CH+CuCl + NH_3 to underset"(Red ppt. )"(Cl-CH_2)-C-=C-Cu+NH_4Cl` Thus, the compound (A) is 3-chloro-1-propyne.

Discussion

50532.	A chloro compound (A) showed the following properties, i. decolourised bromine in CCl_4 (ii). Absorbed hydrogen catalytically. (iii). Gave a red precipitate with ammoniacal cuprous chloride ltbr. (iv). When vaporised 1.49 gm of (A) gave 448 ml of vapours at STP. Identify (A) and write doen the equiation for the reaction is step 3.
Answer» Solution :Step 1: To determine the molecular mass of compound (A): 448 ML of vapours at STP weigh 1.49 gm 22400 ml of vapour at STP will weigh `=(1.49xx22400)/(448)=74.5gm` Thus, the molecular mass of compound (A) is 74.5 a.m.u. step 2. To identify the functional groups: (i). Since (A) decolourises `(Br_2)/(C Cl_4)`, is (A) must be an UNSATURATED compound. This is further supported by the FACT that (A) also absorbs hydrogen catalytically. (ii) Since (A) gave a PRECIPITATE with ammoniacal `CuLl`, it must be a terminal acetyline, ie.e, it must contain the group `(---C--CH)` Step 3. To determine the molecular formula of the compound (A): Molecular mass of `(---C---CH)` group `=12+12+1=25amu` Atomic mass of chlorine`=35.5a.m.u` Molecular mass of the compound `=74.5 amu` molecular mass of the remaining portion of compound `(A)=74.5-25-35.5=14` Since the molecualr mass of a `(CH_2)` group is 14 compound (A) contains a chlorine atom, one `(CH_2)` group, and one terminal acetylene group i.e., `(---C--CH)`, therefore the structure of the organic compound is `underset(3-"chloroprop-1-yne") (ClCH_2)--C-=CH+CuCl+NH_4OHrarrunderset("Copper-3-chlorprop-1-1ynide")(ClCH_2)-=C Cu+NH_4Cl+H_2O`

Discussion

50533.	A chloro compound (A) showed the following properties : (i) decolourised bromine in C CI_4, (ii) absorbed hydrogen catalytically , (iii) gave a precipitate with ammoniacal Cu_2CI_2, (iv) when vapourised 1.49g of (A) gave 448mL of vapour at STP. Identify (A) and write down the equation of reaction at step (iii).
Answer» Solution :The (i) and (ii) properties show that the chloro compound (A) is an unsaturated compound having double or triple bond. The compound GIVES a precipitate with ammoniacal `Cu_2ci_2`. It is , therefore, an ALKYNE having acidic hydrogen ,i.e., `-C-=CH`. Determination of molecular mass: 448mL of the compound WEIGHTS at `STP=1.49 g` `22400mL` of the compound will weigh at STP `=(1.49)/(448)xx22400` Mol. mass `=74.5` Let the formula of the compound be `RCI=-C-=CH` The formula mass `=R+CI+(-C-=CH)=74.5` `R+35.5+25=74.5` `R+60.5=74.5` So, `R=14` i.e., `CH_2` The STRUCTURE of compound (A) is `overset(CI)overset(\|)CH_2-C-=CH`. EQUATION of step (iii). `overset(CI)overset(\|)(2CH)_2-C-=CH+Cu_2CI_2overset(NH_4OH)tooverset(CI)overset(\|)(2CH)_2-C-=C-Cu+2HCI`

Discussion

50534.	(A) Chlorine has higher electron affinity than fluorine. (R) Chlorine is a poor oxidising agent than fluorine.
Answer» Statement-1 (A) and statement-2 (R) are true and statement-2 (R) is the CORRECT explanation for statement-1 (A). Statement-1 (A) and statement-2 (R) are true and statement-2 (R) is not the correct explanation for statement-1 (A) Statement-1 (A) is true, statement-2 (R) is FALSE Statement-1 (A) is false, statement-2 (R) is true Answer :C

Discussion

50535.	A chlorinated alkane has 10.1%C and 0.84% hydrogen by weight. Calculate its empirical formula.
Answer» ANSWER :`CHCl_(3)`

Discussion

50536.	A chloride salt of Rhenium contains 63.6% Re by mass. What is its empirical formula? [Re = 186]
Answer» RECL `ReCl_(2)` `ReCl_(3)` `ReCl_(5)` Answer :C

Discussion

50537.	A chloride of a metal contains 47.23% of the metal. Find out the equivalent weight of the metal.
Answer» ANSWER :31.77

Discussion

50538.	A chemist was performing an experiment to study the effect of varying voltage on the velocity and de Broglie wavelength of the electrons. In first experiment, the electron was accelerated through a potential difference of 1kV and in second experiment, it was accelerated through a potential difference of 2kV. The wavelength of de Broglie waves associated with electron is given by: lamda=(h)/(sqrt(2qVm)) where, V is the voltage through which an electron is accelerated. Putting the values of h, m and q we get: lamda=(12.3)/(sqrt(V))Ã… Q. The velocity of electron will be:
Answer» same in both 1.4 times in second EXPERIMENT than in first experiment double in second experiment than in first experiment four TIEMS in the second CASE than in first case. Answer :b

Discussion

50539.	A chemist while studying the properties of gaseous C C l_(2)F_(2), a chlorofluorocarbon refrigerant, cooled a 1.25 g sample at constant atmospheric prssure of 1.0 atm from 320 K to 293 K . During cooling the sample volume decreased from 274 to 248 mL. Calculate Delta Hand DeltaU for the chlorofluorocaron for this process. For C Cl_(2)F_(2), C_(p) = 80.7 J // ( mol K ).
Answer» Solution :`DeltaH = q_(p) ` and `C_(p)` is heat evolved or absorbed per mole for `1^(@) ` FALL or rise in TEMPERATURE . Here, fall in temperature`= 320- 293 = 27 K` Molar mass of `C C l_(2)F_(2) = 12 + 2 xx 35.5 + 2 xx 19 = 121 gmol^(-1)` `:. `Heat evolved from 1.25 g of the sample on being cooled from 320K to 293 K at constant PRESSURE`= ( 80.7) /( 121) xx 1.25 xx 27 J = 22.51J` Further, `Delta H = Delta U + P Delta V = 22.51J` `P Delta V = 1 atm xx (( 248 0 274))/(100) L = - 0.026 L atm = - 0.026 xx 101.325 J = -2.63 J ` `:.- 22.51 = Delta U - 2.63 J` or ` Delta U = - 22.51 + 2.63 J = - 19.88 J `

Discussion

50540.	A chemist wishes to prepare 6.022 xx 10^(24) molecules of sulphur dioxide. How many gram-atoms of sulphur does the need ?
Answer» Solution :`6.022 xx 10^(23)` molecules of `SO_(2)=1` gram ATOM of `SO_(2)=1` gram atom of S `6.022 xx 10^(24)` molecules of `SO_(2)=10` gram atom of `SO_(2)=10` gram atoms of S.

Discussion

50541.	A chemist was performing an experiment to study the effect of varying voltage on the velocity and de Broglie wavelength of the electrons. In first experiment, the electron was accelerated through a potential difference of 1kV and in second experiment, it was accelerated through a potential difference of 2kV. The wavelength of de Broglie waves associated with electron is given by: lamda=(h)/(sqrt(2qVm)) where, V is the voltage through which an electron is accelerated. Putting the values of h, m and q we get: lamda=(12.3)/(sqrt(V))Ã… Q. In order to get half velocity of electrons in second case, the applied potential will be:
Answer» 0.25 kV 2 kV 0.5 kV 0.75 kV Answer :a

Discussion

50542.	A chemist was performing an experiment to study the effect of varying voltage on the velocity and de Broglie wavelength of the electrons. In first experiment, the electron was accelerated through a potential difference of 1kV and in second experiment, it was accelerated through a potential difference of 2kV. The wavelength of de Broglie waves associated with electron is given by: lamda=(h)/(sqrt(2qVm)) where, V is the voltage through which an electron is accelerated. Putting the values of h, m and q we get: lamda=(12.3)/(sqrt(V))Ã… Q. The wavelength of electron will be:
Answer» 1.4 TIMES in FIRST CASE than in SECOND case 1.4 times in second case than in first case DOUBLE in second case than in first case double in first case than in second case Answer :a

Discussion

50543.	A chemist opened a couborad and found four bottles contaning water solutions, each of which had lost its label. Bottles 1,2,3 contained colourless solutions, while bottle 4 contained a blue solution. The lables from the bottles were lying scattered on the floor of the cupboard. They were:Copper (II) sulphate,""Hydrochloric acid Lead nitrate,""Sodium carbonate By mixing samples of the contents of the bottles, in pairs the chemist made the following observations: {:("Bottle +1 Bottle" 2 rarr, "White precipitate is formed"),("Bottle 1+ Bottle"3 rarr,"White precipitate is formed"),("Bottle 1+ Bottle" 4rarr,"White precipitate is formed"),("Bottle2+ Bottle"3rarr,"Colourless and odourless gas is evolved"),("Bottle 2+ Buttel" 4rarr,"No visivle reaction is observed"),("Bottle 3+ Bottle" 4rarr,"Blue precipitate is formed"):} With the help of the above observations answer the following questions. Which of the following bottle will give precipitate with bottle 1?
Answer» Bottle 2 Bottle 3 Bottle 4 All of these Solution :Bottle `4 RARR CuSO_(4)`, Bottle `2+` Bottle 3 `rarr HCI + Na_(2)CO_(3)` Bottle `1 rArr Pb(NO_(3))_(2)`, Bottle `+1` Bottle `4 rArr PbSO_(4) darr` Bottle `2 rArr HCI`, Bottle `3 rArr Na_(2)CO_(3)` (Since, HCI doesn't react with `CuSO_(4))`

Discussion

50544.	A chemist opened a couborad and found four bottles contaning water solutions, each of which had lost its label. Bottles 1,2,3 contained colourless solutions, while bottle 4 contained a blue solution. The lables from the bottles were lying scattered on the floor of the cupboard. They were:Copper (II) sulphate,""Hydrochloric acid Lead nitrate,""Sodium carbonate By mixing samples of the contents of the bottles, in pairs the chemist made the following observations: {:("Bottle +1 Bottle" 2 rarr, "White precipitate is formed"),("Bottle 1+ Bottle"3 rarr,"White precipitate is formed"),("Bottle 1+ Bottle" 4rarr,"White precipitate is formed"),("Bottle2+ Bottle"3rarr,"Colourless and odourless gas is evolved"),("Bottle 2+ Buttel" 4rarr,"No visivle reaction is observed"),("Bottle 3+ Bottle" 4rarr,"Blue precipitate is formed"):} With the help of the above observations answer the following questions. Which one of the following bottles develops deep blue colour with aqueous ammonia?
Answer» Bottle 1 Bottle 2 Bottle 3 Bottle 4 Solution :Bottle `4 rArr CuSO_(4)`, Bottle `2+` Bottle 3 `rarr HCI + Na_(2)CO_(3)` Bottle `1 rArr Pb(NO_(3))_(2)`, Bottle `+1` Bottle `4 rArr PbSO_(4) DARR` Bottle `2 rArr HCI`, Bottle `3 rArr Na_(2)CO_(3)` (Since, HCI doesn't react with `CuSO_(4))`

Discussion

50545.	A chemist opened a couborad and found four bottles contaning water solutions, each of which had lost its label. Bottles 1,2,3 contained colourless solutions, while bottle 4 contained a blue solution. The lables from the bottles were lying scattered on the floor of the cupboard. They were:Copper (II) sulphate,""Hydrochloric acid Lead nitrate,""Sodium carbonate By mixing samples of the contents of the bottles, in pairs the chemist made the following observations: {:("Bottle +1 Bottle" 2 rarr, "White precipitate is formed"),("Bottle 1+ Bottle"3 rarr,"White precipitate is formed"),("Bottle 1+ Bottle" 4rarr,"White precipitate is formed"),("Bottle2+ Bottle"3rarr,"Colourless and odourless gas is evolved"),("Bottle 2+ Buttel" 4rarr,"No visivle reaction is observed"),("Bottle 3+ Bottle" 4rarr,"Blue precipitate is formed"):} With the help of the above observations answer the following questions. Bottle 3 contains:
Answer» copper (II) sulphate hydrochloric acid lead nitrate sodium carbonate Solution :Bottle `4 rArr CuSO_(4)`, Bottle `2+` Bottle 3 `rarr HCI + Na_(2)CO_(3)` Bottle `1 rArr PB(NO_(3))_(2)`, Bottle `+1` Bottle `4 rArr PbSO_(4) darr` Bottle `2 rArr HCI`, Bottle `3 rArr Na_(2)CO_(3)` (SINCE, HCI doesn't REACT with `CuSO_(4))`

Discussion

50546.	A chemist opened a couborad and found four bottles contaning water solutions, each of which had lost its label. Bottles 1,2,3 contained colourless solutions, while bottle 4 contained a blue solution. The lables from the bottles were lying scattered on the floor of the cupboard. They were:Copper (II) sulphate,""Hydrochloric acid Lead nitrate,""Sodium carbonate By mixing samples of the contents of the bottles, in pairs the chemist made the following observations: {:("Bottle +1 Bottle" 2 rarr, "White precipitate is formed"),("Bottle 1+ Bottle"3 rarr,"White precipitate is formed"),("Bottle 1+ Bottle" 4rarr,"White precipitate is formed"),("Bottle2+ Bottle"3rarr,"Colourless and odourless gas is evolved"),("Bottle 2+ Buttel" 4rarr,"No visivle reaction is observed"),("Bottle 3+ Bottle" 4rarr,"Blue precipitate is formed"):} With the help of the above observations answer the following questions. Which of the following statements is correct for salts contained in bottle 1 and 4?
Answer» Bottle 4 gives white PRECIPITATE with excess of KI solution. Bottle 4 gives white precipitate with excess of `K_(4)[Fe(CN)_(6)]` solution Bottle 1 and 4 both gives precipitate with excess of `NaOH` solution. Bottle 1 gives white precipitate with concentrated HCI solution. Solution :Bottle `4 RARR CuSO_(4)`, Bottle `2+` Bottle 3 `rarr HCI + Na_(2)CO_(3)` Bottle `1 rArr PB(NO_(3))_(2)`, Bottle `+1` Bottle `4 rArr PbSO_(4) darr` Bottle `2 rArr HCI`, Bottle `3 rArr Na_(2)CO_(3)` (Since, HCI doesn't react with `CuSO_(4))`

Discussion

50547.	A chemist dissolves an excess of BaSO_(4) in pure water at 25^(@) C if its K_(sp) = 1 xx 10^(-10) . What is the concentration of barium in the water ?
Answer» `10^(-4)` M `10^(-5)` M `10^(-15)` M `10^(-6)` M Solution :`K_(sp) = [BA^(2+)] [SO_(4)^(2-)]` `1 xx 10^(-10) = (x) (x)` `10^(-5) = x`

Discussion

50548.	A chemist claims that the following reaction is feasible at 298 K SF_(6)(g) + 8 HI(g) rarr H_(2)S( g + 6 HF (g)4I_(2)(g) ] Verify his claim . Given that DeltaG_(f)^(@) for SF_(6)(g) , HI(g) , H_(2)S(g) and HF (g) are - 991.61, 1.30, -33.01 and -270.73kJ mol^(-1) respectively.
Answer» ANSWER :`DELTAG^(@) = - 665.78 KJ MOL^(-1)`

Discussion

50549.	A chemist claims that the following reaction is feasibleat 298 K SF_(6)(g) + 8HI(g) rarrH_(2)S(g+ 6HF (g) +4I_(2)(s) ] Verify his claim. Given that Delta_(f)G^(@)for SF_(6)(g), HI(g) , H_(2)S(g) and HF(g) are - 991.61, 1.30, -33.01 and -270.73kJ mol^(-1) respectively.
Answer» ANSWER :Claim is true `(Delta_(f) G^(@)= - 665.78 kJ MOL^(-1))`

Discussion

50550.	A chemical reaction is spontaneous at 298 Kbut non-spontaneous at 350 K . Which one of the following following s true for this reaction ?
Answer» `{:(DELTA G,DeltaH ,DELTAS),(-,-,+):}` `{:(Delta G,DeltaH ,DeltaS),(+,+,+):}` `{:(Delta G,DeltaH ,DeltaS),(-,+,-):}` `{:(Delta G,DeltaH ,DeltaS),(-,-,-):}` Solution :As reaction is spontaneous at LOW temperature and non-spontaneous at high temperature,i.e., `DELTAG` is-ve at low temperature and `+ve`at high temperature and `DeltaG =DeltaH - T DeltaS`, only ( e) in CORRECT.

Discussion

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