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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 751. |
`Na_(2)S_(2)O_(3)` is prepared by :A. reaching `H_(2)S_(2)O_(3)` with `NaOH`.B. reacting `Na_(2)SO_(4)` with S is alkaline medium.C. heating `NaOH` and SD. reducing `Na_(2)SO_(4)` with S in acidic medium. |
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Answer» Correct Answer - C `6NaOH(aq)+4S(s)overset(Delta)toNa_(2)S_(2)O_(2)(aq)+3H_(2)O(l)`. |
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| 752. |
`HCOOH underset(conc. H_(2)SO_(4)) overset(373K) rarr H_(2)O+(X)` `C(s)+H_(2)O overset(423-1273K) rarr (X)+H_(2)(g)` Select the correct statement about (X):A. (X) is a colourless, odourless, odourless and almost water insoluble gasB. (X) is highly poisonous and burns with blue flameC. When (X) gas is passed through `PdCl_(2)` solution balck ppt. is formedD. All of the above |
| Answer» Correct Answer - D | |
| 753. |
Ammonium dichromate on heating liberates a gas. The same gas will be obtained by :A. heating `NaNO_(2)` and `NH_(4)Cl`.B. treating `H_(2)O_(2)` "with" `NaNO_(2)`.C. "passing ammonia gas over red hot" `CuO`.D. treating of hydroxyl with`KMnO_(4)`in neutal medium. |
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Answer» Correct Answer - A,C,D (A) `NaNO_(2)NH_(4)Cl to NaCI+NH_(4)NO_(2), " "NH_(4)NO_(2)overset(Delta)to N_(2)O+2H_(2)O` (B) `H_(2)Oto H_(2)O+[O],NaNO_(2)+[O]toNaNO_(3)` (C ) `2NH_(3)+3CuOto 3Cu+N_(2)+3H_(2)O` (D) `2KMn^(+7)O_(4)^(-)+2NH_(3)to 2KOH+2MnO_(2)+N_(2)O+2H_(2)O` |
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| 754. |
How many dative bonds are there in `H_2SO_4` molecule? |
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Answer» Correct Answer - A `O=undersetunderset(OH)|oversetoverset(O)(||)S-OH` NO dative bond |
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| 755. |
When `SO_2` is passed through bromine water products formed areA. `H_2SO_4 + HBr `B. `H_2O` and HBrC. S and `H_2O`D. HBr and S |
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Answer» Correct Answer - A `Br_2 + SO_2 + 2H_2O to 2HBr + H_2SO_4` |
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| 756. |
The oxidation number of sulphur in iron pyrites isA. `-1`B. `+2`C. `+2`D. `+3` |
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Answer» Correct Answer - A Iron pyrite is `FeS_2`. Fe is +2 , S is -1 |
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| 757. |
The S-S-S bond angle in `S_8` molecule isA. `109.5^(@)`B. `105^(@)`C. `110^(@)`D. `60^(@)` |
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Answer» Correct Answer - B The S-S-S bond angle in `S_(8)` molecules is `105^(@)` |
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| 758. |
Which of the following are peroxoacids of sulphur ?A. `H_(2)SO_(5) and H_(2)S_(2)O_(8)`B. `H_(2)SO_(5) and H_(2)S_(2)O_(7)`C. `H_(2)S_(2)O_(7) and H_(2)S_(2)O_(8)`D. `H_(2)S_(2)O_(6) and H_(2)S_(2)O_(7)` |
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Answer» Correct Answer - A `H-O-O-underset(O)underset(||)overset(O)overset(||)S-O-H(H_(2)SO_(5))` `H-O-o-underset(O) underset(||) overset(O) overset(||)S-underset(O) underset(||) overset(O) overset(||)S-O-O-H(H_(2)S_(2)O_(8))` Both `H_2SO_(5) and H_2S_2O_(8)` have peroxide linkages . |
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| 759. |
Sulphur on boiling with `NaOH` solution givesA. `Na_(2)S_(2)O_(3)+NaHSO_(3)`B. `Na_(2)S_(2)O_(3)+Na_(2)S`C. `Na_(2)SO_(3)+H_(2)S`D. `Na_(2)SO_(3)+SO_(2)` |
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Answer» Correct Answer - B `3S + 4NaOH overset("boling")(rarr) Na_(2) S_(2) + Na_(2)S` |
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| 760. |
In borax bead test, which compound is formed?A. OthoborateB. MetaborateC. Double oxideD. Tetraborate. |
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Answer» Correct Answer - B is the correct anser. |
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| 761. |
Statement-I: `NaBO_(3)//OH^(-)` can be used for oxidation of `Cr^(3+) "to" Cr^(6+)` Statement-II: In alkaline medium `NaBO_(3)` produces `H_(2)O_(2)`A. If both statement -I & Statement-II are true & the Statement-II is correct explaination of the statement-I.B. If both Statement-I & Statement-II are true but Statement-II is not a correct explainatin of Statement-I.C. If Statement-I is True but the Statement-II is FalseD. If the Statement-I is False but the Statement-II is True |
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Answer» Correct Answer - A `NaBO_(3)` contains peroxy linkage. |
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| 762. |
An aqueous solution of borax is (a) neutral , (b) amphoteric , (c ) basic, (d) acidic |
| Answer» Borax is a salt of a strong base `(NaOH)` and a weak acid `(H_(3)BO_(3))`, therefore, it is basic in nature, i.e, option (c ) is correct. | |
| 763. |
Incorrect statements for pyrophosphorus acid `(H_(4)P_(2)O_(5))` isA. It contains P in +5 oxidation stateB. It is dibasic acidC. It is strongly reducing in natureD. It contains one P-O-P bond |
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Answer» Correct Answer - A It contains phosphorus in +3 oxidation state . |
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| 764. |
`B_(4)C` is also known asA. Cast steelB. Carbon boronC. Boron carbideD. Carbon steel with boron impurity |
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Answer» Correct Answer - C `B_(4)C=` Boron carbide |
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| 765. |
Iodine flakes when rubbed with liquor ammonia give dark brown ppt. ofA. `NI_3`B. `NH_4I`C. `NI_3.NH_3`D. `NH_4. NI_3` |
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Answer» Correct Answer - C `2NH_3 + 3I_2 to NI_3 . NH_3 + 3HI` |
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| 766. |
in the manufactring of bromine from sea water, the mother liquor contaning bromides is treated withA. `CO_(2)`B. `Cl_(2)`C. `I_(2)`D. `SO_(2)` |
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Answer» Correct Answer - B `MgBr_(2)+Cl_(2)rarrMgCl_(2)+Br_(2)` `Cl_(2)` removes `Br_(2)` from `MgBr_(2)` present in mother liquor. |
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| 767. |
On small scale, boron is best isolated by reducing boron trioxide withA. Metallic zincB. Metallic aluminiumC. Metallic copperD. Metallic magnesium |
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Answer» Correct Answer - D `B_(2)O_(3)+3Mgoverset(1100^(@)C)to2B+3MgO` |
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| 768. |
Which one is the best reducing agent ?A. `F^-`B. `Cl^-`C. `I^-`D. `Br^-` |
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Answer» Correct Answer - C `I_2` is weakest oxidising agent hence `I^-` is the strongest reducing agent. |
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| 769. |
Iodine stains on clothes can be removed byA. NaClB. NaBrC. KlD. `Na_2S_2O_3` |
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Answer» Correct Answer - D `2Na_2S_2O_3 + I_2 to Na_2S_4O_6 + 2NaI` |
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| 770. |
The increasing order of reducing power of the halogen acids isA. HF lt HCl lt HBr lt HIB. HI lt HBr lt HCl lt HFC. HBr lt HCl lt HF lt HID. HCl lt HBr lt HF lt HI |
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Answer» Correct Answer - A HF lt HCl lt HBr lt HI depends on size of halogen |
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| 771. |
Which halogen shows some metallic character ?A. `F_2`B. `Br_2`C. `I_2`D. `Cl_2` |
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Answer» Correct Answer - C Iodine with large atomic size, low ionisation enthalpy and electronegativity show some metallic property. It is solid and has metallic lustre. |
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| 772. |
Which of the following shows greatest mert pair effect ?A. `F_2`B. `Cl_2`C. `Br_2`D. `I_2` |
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Answer» Correct Answer - D `I_2` has highest inert pair effect |
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| 773. |
The strongest reducing agent is :A. `F^(-)`B. `Cl^(-)`C. `Br^(-)`D. `I^(-)` |
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Answer» Correct Answer - D |
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| 774. |
Which of the following halogens has the highest melting point ?A. `F_2`B. `Cl_2`C. `Br_2`D. `I_2` |
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Answer» Correct Answer - D M.P./B.P. increases down the group `I_2` being solid shows highest M.P. |
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| 775. |
`(CH_(3))_(3) N` is basic but `(CF_(3))_(3)N` is not basic. Explain why ? |
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Answer» N has a lone pair of electrons. But due to higher electronegativity of C `(2.5)` than that of `H(2.1)`, `CH_(3)` acts as an electron-donating group. It increases the electron density on N in `(CH_(3))_(3)N`. As a result, the lone pair of electrons on N in `(CH_(3))_(3)N` in easily available for potenation and hence `(CH_(3))_(3)N` acts a base. In contrast, due to much higher electronegativity of `F(4.0)` than that of `(2.5)`, `CF_(3)` acts a strong electron-withdrawing group. It considerably decreases the electron density of N in `(CF_(3))_(3)N`. As a result, the lone pair of electrons on N in `(CF_(3))_(3)N` is not available for protonation and hence `(CF_(3))_(3)N` does not act as a base. |
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| 776. |
The law of triad is applicable to a group ofa)`Cl, Br, I`b)C,N,Oc)`Na,K,Rb`d)`H,O,N`A. C,N,OB. Cl,Br, IC. Na,K,RbD. None of these |
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Answer» Correct Answer - B Atomic weight of Br is the average of Cl and I |
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| 777. |
Sodium chloride when heated with conc. `H_(2)SO_(4)` and solid potassium dichromate givesA. Chromic chlorideB. Chromyl chlorideC. Chromous chlorideD. None of these |
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Answer» Correct Answer - B `4NaCl+K_(2)Cr_(2)O_(7)+3H_(2)SO_(4)rarrunderset("Chromyle chloride")(K_(2)SO_(4)+2Na_(2)SO_(4))+2Na_(2)SO_(4)+2CrO_(2)+3H_(2)O` |
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| 778. |
Why is diamond a had conductor of electricity but a good conductor of heat ? |
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Answer» Conduction of electricity of essentially requires movement of electrons while conduction of heat does not necessarily require movement of electrons. Since in diamond, all the electrons are firmly held C-C, `sigma`-bonds, there are no free electrons in a diamond crystal. Therefore, diamond is a bad conductor of electricity. In contrast, conduction of heat is due to thermal vibrations from one atom to the other which is easier in a compact crystal of diamond. |
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| 779. |
A solution of `HCl` in water is good conductor while gaseous hydrogen chloride is not. This is due to the reason thatA. Water is a good conduter of electricityB. `HCl` in waterr ionisesC. Gas cannot conduct elctricity but water canD. None of these |
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Answer» Correct Answer - B `Hcloverset(H_(2)O)rarrunderset(aq)H^(+)+underset(aq)(Cl^(-)` |
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| 780. |
Which of the following halogen acid is a liquid ?A. `HF`B. `HCl`C. `HBr`D. `HI` |
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Answer» Correct Answer - A `HF` is liquid |
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| 781. |
`Cl_2O_7` can be regarded as an anhydride ofA. hypochlorous acidB. chlorous acidC. chloric acidD. per chloric acid |
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Answer» Correct Answer - D Per chloric acid is `HClO_4` |
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| 782. |
Chlorine is formed when dil HCl is treated withA. `KMnO_4`B. `MnO_2`C. `K_2Cr_2O_7`D. All of these |
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Answer» Correct Answer - D Preparation of `Cl_2.` Dil . HCl reacts with `KMnO_4,MnO_2, K_2Cr_2O_7` to liberate `Cl_2` |
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| 783. |
Which of the following trend correctly represent the stability of oxides of halogens?A. `ClgtIgtBr`B. `IgtCIgtBr`C. `BrgtCIgtI`D. `BrgtIgtCl` |
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Answer» Correct Answer - B Iodine-oxygen bond is stable due to greater polarity of the bond. Stability of chlorine-oxygen bond is due to multiple bond formation involving `d`-orbitals of the chlorine atom. |
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| 784. |
How is chlorine obtained in the laboratory ? How does it react with the following ? excess `NH_(3)` |
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Answer» In the laboratory chlorine is prepared by the oxidation of HCl with `MnO_(2)`. `4HCl+"MnO"_(2)to"MnCl"_(2)+2" H"_(2)O+Cl_(2)uarr` `Cl_(2)` reacts with excess of `NH_(3)`, Nitrogen and ammonium chloride are formed. `8" NH"_(3)+3" Cl"_(2)to6" NH"_(4)Cl+N_(2)uarr` |
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| 785. |
How is chlorine obtained in the laboratory ? How does it react with the following ? KI |
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Answer» In the laboratory chlorine is prepared by the oxidation of HCl with `MnO_(2)`. `4HCl+"MnO"_(2)to"MnCl"_(2)+2" H"_(2)O+Cl_(2)uarr` `Cl_(2)` reacts with KI to liberate iodine `Cl_(2)+2" KI"to2" KCl"+I_(2)uarr` |
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| 786. |
How is chlorine prepared in the laboratory ? How does it react with the following ? Iodine |
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Answer» In the laboratory chlorine is prepared by the oxidation of HCl with `MnO_(2)`. `4" HCl"+"MnO"_(2)to"MnCl"_(2)+2" H"_(2)O+Cl_(2)uarr` `Cl_(2)` reacts with Iodine to form Icl `underset(("Equi molar"))(I_(2)+Cl_(2)to)2ICl` |
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| 787. |
Which one is least basic?A. `BI_(3)`B. `BBr_(3)`C. `BCl_(3)`D. `BF_(3)` |
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Answer» Correct Answer - D `BF_(3)` accept lone pair of electrons. |
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| 788. |
How is chlorine prepared in the laboratory ? How does it react with the following ? acidified `FeSO_(4)` |
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Answer» In the laboratory chlorine is prepared by the oxidation of HCl with `MnO_(2)`. `4" HCl"+"MnO"_(2)to"MnCl"_(2)+2" H"_(2)O+Cl_(2)uarr` `Cl_(2)` reacts with acidified `FeSO_(4)` and ferric ions are formed. `2" FeSO"_(4)+H_(2)SO_(4)+Cl_(2)to"Fe"_(2)(SO_(4))_(3)+2" HCl"` |
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| 789. |
In `K` solution, `I_(2)` readily dissolved and formsA. `I^(-)`B. `KL_(2)`C. `K_(2)^(-)`D. `Kl_(3)` |
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Answer» Correct Answer - D `Kl+I_(2)rarrKl_(3)` |
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| 790. |
Which halogen does not show variable oxidation state?A. `F_(2)`B. `CL_(2)`C. `Br_(2)`D. `I_(2)` |
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Answer» Correct Answer - A Florine always show `-1` oxidation state. |
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| 791. |
How is chlorine prepared by electrolytic method ? Explain its reaction with NaOH |
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Answer» Preparation of chlorine by electrolytic method : Chlorine is obtained by the electrolysis of brine solutions (Conc. NaCl). `Cl_(2)` gas is liberated at anode. `2NaCl to2" Na"^(+)+2Cl^(-)` `2" H"_(2)O+2e^(-)to2OH^(-)+H_(2)` (cathode) `2" Cl"^(-) to Cl_(2)+2E^(-)` (anode) i) NaOH : Chlorine reacts with cold dil. NaOH to from sodium hypochlorite. `Cl_(2)+2" NaOH"to"NaCl"+"NaOCl"+H_(2)O` ii) `Cl_(2)` reacts with hot conc. NaOH to form sodium chloride and sodium chlorate. `3Cl_(2)+6" NaOH"to5" NaCl"+"NaClO"_(3)+3" H"_(2)O` |
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| 792. |
Chlorine can removeA. `Br` from `NABr` solutionB. `F` from `NaF` solutionC. `Cl` from `NaCl` solutionD. `F` from `CaF_(2)` solution |
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Answer» Correct Answer - A `Cl_(2)+2NaBrrarr2NaCl+Br_(2)` |
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| 793. |
Which of the following hydrogen halide has the highest boiling point?A. `HF`B. `HCl`C. `HBr`D. `HI` |
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Answer» Correct Answer - A In `HF` the molecules aggregate because of intermolecular hydrogen bonding. Hence, it has highest boiling point. |
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| 794. |
Cryolite and Calich are the source of halogens `A` and `B` resctively. `A` and `B` areA. Sodium, BromineB. Sodium, IodineC. Fluorine, IodineD. Fluorine, Bromine |
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Answer» Correct Answer - C Cryolite is `Na_(3)[AIF_(6)]-`Source of fluorine Calich or crude chile saltpeter contains about `0.2%` of `NaIO_(3)` (sodium iodate)`. |
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| 795. |
A gas reacts with `CaO`, but not with `NaHCO_(3)`. The gas isA. `CO_(2)`B. `Cl_(2)`C. `N_(2)`D. `O_(2)` |
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Answer» Correct Answer - B `CaO+Cl_(2)rarrCaOCl_(2)` `NaHCO_(3)+I_(2)Cl_(2)rarr`No reaction |
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| 796. |
How is chlorine prepared by electrolytic method ? Explain its reaction with `NH_(3)` under different conditions. |
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Answer» Preparation of chlorine by electrolytic method : Chlorine is obtained by the electrolysis of brine solutions (Conc. NaCl). `Cl_(2)` gas is liberated at anode. `2NaCl to2" Na"^(+)+2Cl^(-)` `2" H"_(2)O+2e^(-)to2OH^(-)+H_(2)` (cathode) `2" Cl"^(-)to Cl_(2)+2e^(-)` (anode) i) `Cl_(2)` reacts with excess of `NH_(3)`, Nitrogen and ammonium chlorate are formed. `8" NH"_(3)+3" Cl"_(2)to6" NH"_(4)Cl+N_(2)uarr` ii) `NH_(3)` reacts with excess of `Cl_(2)` to form `NCl_(3)` and HCl. `NH_(3)+3" Cl"_(2)tounderset("trichloride")underset("Nitrogen")(NCl_(3)+)3" HCl"` |
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| 797. |
When `Kbr` is treated with concentrated `H_(2)SO_(4)` reddich brown gas evolved, gas isA. Mixture of bromine and `HBr`B. `HBr`C. BromineD. None of these |
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Answer» Correct Answer - C `2KBr+3H_(2)SO_(4)+MnO_(2)overset(Delta)(rarr)2KHSO_(4)+MnSO_(4)+2H_(2)O+Br_(2)` |
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| 798. |
Bromine is obtained on commercial scale fromA. CalicheB. CarnalliteC. Common saltD. Fluorine, Bromine |
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Answer» Correct Answer - B Carnallite is `KCl.MgCl_(2).6H_(2)O`. The mother liquor life after crytallisation of `KCl` from carnallite contain about `0.25%` of bromine as `MgBr_(2)` and `KBr`. |
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| 799. |
Chlorine cannot be prepared by the action of `HCl` onA. `MnO_(2)`B. `KMnO_(4)`C. `NaCl`D. `K_(2)Cr_(2)O_(7)` |
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Answer» Correct Answer - C Chlorine cannot be prepared by action of `HCl` on `NaCl`. |
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| 800. |
What is tin cry ? |
| Answer» Correct Answer - When bent the metal produces a cracking sound due to rubbing of crystals over one another is known as tin cry | |