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InterviewSolution
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.
| 301. |
Nitric oxide`(NO)`is prepared in the laboratory byA. the reduction of dilute `HNO_(3)` with `Cu`B. the catalytic oxidation of ammoniaC. subjecting a mixture of nitrogen and oxygen to an electric sparkD. warming potassiun nitrate with dilute sulphuric acid and ferrous sulphate solution |
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Answer» Correct Answer - 1 Coppor chips are taken in a woulfe-bottle and some water is added. Concentrated nitric acid is poured thorugh the thistle funnel and tha nitric oxide liberated is collected over water. `3Cu+8HNO_(3)rarr3Cu(NO_(3))_(2)+2NO+4H_(2)O` Nitric oxide is an important intermediate in the manufacture of nitric acid by the catalytic oxidation of ammonia ( ostwald process): `4NH_(3)+5O_(2)overset("Pt gauze")rarr4NO+6H_(2)O` It was also important in the obsolete Birkeland-Eyde process which involved nitrogen and oxygen, `N_(2)(g)+O_(2)(g)overset("Electric")underset("spark")rarr2NO(g)` `NO` molecule is an atmospheri pollutant commonly formed as a sode reaction inhigh -comparised internal combustion engines when dinitrogen and dioxygen are compressed and sparked: `N_(2)(g)+O_(2)(g) hArr 2NO(g)` A pure sample of nitric oxide is obtained when a mixture of `KNO_(3), FeSO_(4)` and dilute `H_(2)SO_(4)` is heated: `{:(2KNO_(3)+H_(2)SO_(4) rarr K_(2)SO_(4) +2HNO_(3)),(2HNO_(3) rarr H_(2)O+2NO+3O),([2FeSO_(4)+H_(2)SO_(4)+O rarr Fe_(2)(SO_(4))_(3)+H_(2)O]xx3),(bar(2KNO_(3)+6FeSO_(4)+4H_(2)SO_(4) rarr K_(2)SO_(4)+3Fe_(2)(SO_(4))_(3)+2NO+4H_(2)O)):}` |
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| 302. |
In the `N_(2)O`molecule theA. `N-N` bond length is greater than `N-O` bond lengthB. `N-N` bond length is shorter than the `N-O` bond lengthC. `N-N` bond length is nearly equal to `N-O` bond lengthD. `N-N` bond length is half of the `N-O` bond length |
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Answer» Correct Answer - 2 Dinitrogen oxide `(N_(2)O)` is isoelectronic with `CO_(2)` and the `N_(3)^(-)` ion. However, contrary to what one might expect, the atoms are arranged asymmetrically, with a `N-N` bond length of `113` pm and a `N-O` bond legth of `119` pm. |
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| 303. |
Sodium azide `(NaN_(3))`is prepared by heating a mixture ofA. `NaNH_(2)` and `N_(2)O`B. `NaNO_(2)` and `N_(2)O`C. `Na_(3)PO_(4)` and `N_(2)O`D. `NH_(4)NO_(3)` and `NCl_(3)` |
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Answer» Correct Answer - 1 `N_(2)O` is important in the preparation of sodium azides and hence also of the other azides: `N_(2)O+2NaNH_(2)rarrNaN_(3)+NH_(3)+NaOH` |
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| 304. |
Phosphorus is obtained by reducingA. phophatic fertilizers with boron and alumina in an electric furnanceB. phosphate rock with silica and iron oxide in an electric furnaceC. phosphate rock with coke at a high temperature in the presence of silica in an electric furnanceD. phosphate rock with sulphur and alumina. |
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Answer» Correct Answer - 3 phosphorus is such a reactive element that quite extreme methods have to be used to extract it from its compounds, The raw material is calcium phosphate. This compound is found in large deposits whose origin is not well understood, althoughbthey may have been the result of the interaction of the calcium carbonate of coral reefs with the phosphate dropping of seabrids over a period of hundreds of thousands of years. Processing of phosphate rock is highly dependent on electric energy. As a result, the ore is usually shipped to countries where electric power is abundant and inexpensive, such as North America and Europe. The conversion of phosphate rock to the element is accomplished in a very large electric furnace containing`60`-tonne carbon electrodes. In this electrothermal process, the furnace is filled with a mixture of ore, sand and coke and a current of about `1,80,000 A(at 500V)` is applied across the electrodes. At `1500^(@)C` operating temperature of the furnace, the calcium phosphate react with carbon monoxide and gaseous tetraphosphorus: `2Ca_(3)(PO_(4))_(2)(s)+10CO(g)overset(Delta)rarr6CaO(s)+10CO_(2)(g)+P_(4)(g)` The carbon dioxide is then reduced back to carbon monoxide by the coke, `CO_(2)(g)+C(s)rarr2CO(g)` Some of the gas is reused, but the remainder escapes from the furnace. The calcium oxide react with silicon dioxide (sand) to give calcium silicate (slag) : `CaO(s)+SIO_(2)(s)rarrCaSiO_(3)(l)` The escaping carbon monoxide is burned and the heat is used to dry the three raw materials: `2CO(g)+O_(2)(g)rarr2CO_(2)(g)` To condense the gaseous tetraphosphours, it is plumed into a tower and sprayed with water. The liquefied phosphorus collects at the bottom of the tower and is drained into holding tanks. The average furnace produces about `5` tonnes of tetraphosphorurs per hour. Another version Sand `("silica "SiO_(2))` is added to remove the calcium as a fluid slag (calcium silicate) and to drive off the phosphorus as `P_(4)O_(10)`. The `P_(4)O_(10)` is reduced to phosphorus by`C`. At this temperature gaseous phosphours distills off, mainly as `P_(4)` but with some `P_(2)`. This is condensed to white phosphorus `P_(4)` by passing the gas through water. |
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| 305. |
Which of the following is not correct in the context of the `NO_(3)^(-)` ions?A. The bond order of each `N-O` bond is `4//3`B. The bond order of each `N-O` bond is `3//2`C. The geometry and shape of the `NO_(3)^(-)` ion is planar triangularD. All the three oxygen atoms are equivalent |
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Answer» Correct Answer - 2 The geometry as well as shape of the nitrate ion is a planar triangle. All three `O` atoms are equivalent. In addition to the `sigma` bond. Four- centre `pi` molecular orbitals cover the`N`and the three`O`atoms. Each of the `N-O` bonds has a bond order of,`1(1)/(3)(1.33)`, 1 from the `sigma` bond and `1//3` from the `pi` bond. |
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| 306. |
Identify the CORRECT statement from the following?A. `SI_(6)` is known but not `SF_(6)`B. `SO_(2)` is acidic oxide of sulphur.C. Gamma `SO_(3)` is one of the pure form of `SO_(3)` and exist as a cyclic trimer.D. None of these |
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Answer» Correct Answer - B::C |
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| 307. |
Nitrogen is used to fill electric bulbs becauseA. it is provides good illuminationB. it does not support combustionC. it is heavier than airD. it is highly reactive |
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Answer» Correct Answer - 2 Dinitrogen does not burn or support combustion .It is extremely unreactive towards most elements and compounds because of the stability of nitrogen -nitrogen triple bond. The `N equiv N` bond enthalpy is `942" kJmol"^(-1)` compared with `167" kJmol"^(-1)` for the `N-N` bond enthalpy. Thus `N_(2)(g)` is used to provide an inert atmosphere during welding and for certain metallurgical processes where oxidation might otherwise occur and for filling electrical lamps. |
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| 308. |
Liquid nitrogen is used to makeA. fertilizersB. iceC. solid semiconductorsD. solid superconductors |
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Answer» Correct Answer - 4 Because it provide low temperature large quantities of nitrogen are also used as a blanketing gas, whose purpose is to protect a material from oxygen during processing or storage. |
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| 309. |
Draw the structures of `(i) H_(2)S_(2)O_(8) (ii) XeO_(4)`. |
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Answer» (i) For structure of `H_(2)S_(2)O_(8)`, (ii) For structure of `XeO_(4)` . |
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| 310. |
How are `XeO_(3) " and " XeOF_(4)` prepared ? |
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Answer» Preparation of `XeO_(3)`. By complete hydrolysis of `XeF_(6)`. `XeF_(6) +3H_(2)O to XeO_(3)+6HF`. Preparation of `XeOF_(4)`. By partial hydrolysis of `XeF_(6)`. `XeF_(6) +H_(2)O to XeOF_(4)+2HF`. |
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| 311. |
What is the basicity of pyrophosphoric acid ? |
| Answer» Pyrophosphoric acid `(H_(4)P_(2)O_(7))` is a tetrabasic acid. Its basicity is four. | |
| 312. |
Which of the following is the correct statement for `PH_(3)`?A. It is extermely soluble in waterB. it is less basic then `NH_(3)`C. It does not show reducing propertiesD. it is nontoxic |
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Answer» Correct Answer - 2 Phosphine is a very weak base. In fact ,the phosphonium ion `PH_(4)^(+)` ,the equivalent of the ammonium ion,is difficult to prepare. `PH_(3)`, unlike `NH_(3)`, is not very soluble in water: aqueous solution are neutral. Relative to `NH_(3)`, it is very poisonous. Phosphine is a much more powerful reducing agent than ammonia,converting silver and copper (II) salts in solution to their phosphides which subsequently react to give the free metals: `6Ag^(+)(aq)+PH_(3)(g)+3H_(2)(l)O rarr6Ag(s)+H_(3)PO_(3)(aq)+6H^(+)(aq.)` |
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| 313. |
Why is `K_(a_(2)) ltlt K_(a_(1))` for `H_(2) SO_(4)` in water ? |
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Answer» `H_(2) SO_(4(aq)) + H_(2) O_((l)) to H_(3)O_((aq))^(+) + HSO_(4(aq))^(-), K_(a_(1)) gt 10` `H_(2) SO_(4(aq))^(-) + H_(2) O_((l)) to H_(3)O_((aq))^(+) + SO_(4(aq))^(-)," " K_(a_(2)) = 1.2 xx 10^(-2)` It can be noticed that `K_(a_(1)) gt gt K_(a_(2))` This is because a neutral `H_(2)SO_(4)` has a much higher tendency to lose a proton than the negatively charged `HSO_(4)^(-)`. Thus, the former is a much stronger acid than the latter. |
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| 314. |
Which of the following is correct?A. When aluminium of phosphide is treated with dil. Sulphuric acid `PH_(3)` is evolvedB. `PH_(4)I+NaOH` forms `PH_(3)`C. one mole of calcium phosphide on reaction with excess of water gives two moles of phoshineD. All of these |
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Answer» Correct Answer - 4 `2AIP+3H_(2)SO_(4)rarrAl_(2)(SO_(4))_(3)+2PH_(3)` `PH_(4)I+NaOH rarrPH_(3)+NaI+H_(2)O` `Ca_(3)P_(2)+6H_(2)Orarr3Ca(OH)_(2)+2PH_(3)` |
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| 315. |
Phosphorus trichloride can be obtained from white phosphorus by the action ofA. `Cl_(2)`B. `SOCl_(2)`C. `SO_(2)Cl_(2)`D. Both (1) and (2) |
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Answer» Correct Answer - 4 Phosphrous trichloride (a colourless liquid)is produced when chlorine gas reacts with an excess of white phosphorus: `P_(4)(s)+6Cl_(2)(g)rarr4PCl_(3)(l)` An excess of chloride results in phosphrous pentachloride (a white solid), `P_(4)(s)+10Cl_(2)(g)rarr4PCl_(5)(g)` Action of thionyl chloride on white phosphorus yields phosphorus trichloride while action of sulphuryl chloride on white to phosphorus yields phosphorus pentachloride: `P_(4)+8SOCl_(2)rarr4PCl_(3)+4SO_(2)+2S_(2)Cl_(2)` `P_(4)+10SO_(2)Cl_(2)rarr4PCl_(5)+10SO_(2)` |
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| 316. |
Which of the following is incorrect about phosphorus trichloride?A. It is widely used in organic chemistry to convert carboxylic acids to alkyl chlorides.B. It is oxidized by `O_(2)` or `P_(4)O_(10)` to give phosphorus oxochlorideC. it is an unsaturated compoundD. it acts as a reducing agent |
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Answer» Correct Answer - 1 It convert carboxylic acids to acid chlorides `PCl_(3)+3RCO_(2)Hrarr3RCOCl+H_(3)PO_(3)` Catalytic oxidation of phosphorus trichloride gives phosphorus oxychloride: `2PCl_(3)(l)+O_(2)(g)rarr2POCl_(3)(l)` `6PCl_(3)+P_(4)O_(10)+6Cl_(2)rarr10POCl_(3)` It directly combines wiht `Cl_(2),O_(2)` and `S` incdicating that it is an unsatureed compound: `PCl_(3)+Cl_(2)rarrPCl_(5)` `2PCl_(3)+O_(2)rarr2POCl_(3)` `PCl_(3)+SrarrPSCl_(3)` It acts as a reducing agent `PCl_(3)+SO_(2)Cl_(2)rarrPCl_(5)+SO_(2)` `PCl_(3)+SO_(3)rarrPOCl_(3)+SO_(2)` `3PCl_(3)+SOCl_(2)rarrPOCl_(3)+PSCl_(3)+PCl_(5)` |
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| 317. |
Which of the following element was used on the floor in the Hanging Gardens of Babylon (one of the wonders of the ancient world)?A. `Sn`B. `Si`C. `Pb`D. `Ge` |
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Answer» Correct Answer - C Lead sheet was used to prevent water escaping. |
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| 318. |
Give colour of bead produced when glassy bead reacts with CuO |
| Answer» Correct Answer - Blue bead | |
| 319. |
Which of the following reactions is not used to prepare diborane?A. `BF_(3) + NaH overset(180^(@)C)rarr`B. `B_(2)O_(3) + CaF_(2) + conc.H_(2)SO_(4) rarr`C. `Na[BH_(4)] + I_(2) underset("solution")overset("Diglyme")rarr`D. `(C_(2)H_(5))_(2)O.BF_(3) + LiAlH_(4) rarr` |
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Answer» Correct Answer - B It leads to the formation of boron trifluoride: `B_(2)O_(3) + 3CaF_(2) + conc.3H_(2)SO_(4) overset(Delta)rarr 2BF_(3) + 3CaSO_(4) + 3H_(2)O` Other possibility is `B_(2)O_(3) + 6NH_(4)BF_(4) overset(Delta)rarr 8BF_(3) + 6NH_(3) + 3H_(2)O` (1) `2BF_(3) + 6NaH overset(180^(@)C)rarr B_(2)H_(6) + 6NaF` (2) `2Na[BH_(4)] + I_(2) rarr B_(2)H_(6) + H_(2) + 2NaI` (4) `4[Et_(2)O.BF_(3)] + 3Li[AlH_(4)] rarr 2B_(2)H_(6) + 3Li[AlF_(4)] + 4Et_(2)O` |
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| 320. |
Which is not the use of orthoboric acid?A. As an antiseptic and eye wash.B. In glass industryC. In glazes for pottery.D. In borax - bead test |
| Answer» Correct Answer - D | |
| 321. |
Orthoboric acid containsA. `T`-shaped `BO_(3)^(3-)` unitsB. pyramidal `BO_(3)^(3-)` unitsC. triangular `BO_(3)^(3-)` unitsD. irregular tetrahedral `BO_(3)^(3-)` units |
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Answer» Correct Answer - C In boric acid, trigonal planar `BO_(3)^(3-)` units are joined by `H`-bonds to give a layered structure. |
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| 322. |
When boric acid is heated at `160^(@)C`, the product isA. boric anhydrideB. metaboric acidC. tetraboric acidD. pyroboric acid |
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Answer» Correct Answer - C Boric acid, on heating, loses water in three different stages at different temperatures ultimately giving boron trioxide: `H_(3)BO_(3) overset(100^(@)C)rarrH_(2)O underset("Metaboric acid")(HBO_(2))` `4HBO_(2) underset(-H_(2)O)overset(100^(@)C)rarrunderset(acid)underset("Tetraboric")(H_(2)B_(4)O_(7)) underset(heat)overset(Red)rarr 2B_(2)O_(3) + H_(2)O` |
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| 323. |
The chemical name of borax isA. sodium orthoborate decahydrateB. sodium metaborate decahydrateC. sodium tetraborate decahydrateD. sodium borate decahydrate |
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Answer» Correct Answer - C Borax is `Na_(2)B_(4)O_(7) . 10H_(2)O`. |
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| 324. |
Which of the following group 13 elements does not show the inert pair effect?A. `Al`B. `Ga`C. `In`D. `Tl` |
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Answer» Correct Answer - A Only `Ga, In`, and `Tl` are able to exhibit `+1` and `+3` oxidation numbers in their compounds. |
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| 325. |
Anhydrous `AlCl_(3)` produces fumes in the air because ofA. oxidationB. reductionC. dimerizationD. hydrolysis |
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Answer» Correct Answer - D Anhydrous `AlCl_(3)` is partially hydrolyzed with atmospheric moisture to liberate `HCl` gas. Moist `HCl` appears white in color. |
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| 326. |
The self-protective oxide film on `Al` can be removed byA. reacting with `Cl_(2)`B. adding conc. `HNO_(3)`C. amalgamating with `Hg`D. boiling with water |
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Answer» Correct Answer - C Amalgamation dissolves the oxide film. |
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| 327. |
When `SO_(2)` is passed into an `Na_(2)CO_(3)` solution, it producesA. `NasO_(3)` and `CO_(2)`B. `NaHSO_(4)` and `CO_(2)`C. `NaSO_(3), NaHSO_(3)` and `CO_(2)`D. `H_(2)SO_(4)` |
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Answer» Correct Answer - 2 It is acidic oxide.it dissolves in water forming sulphuric acid, which is a stronger acid than carbonic acid.Therefore ,it decomposes carbonates and bicarbonates evolving `CO_(2)` gas: `Na_(2)CO_(3)+2SO_(2)+H_(2)O rarr 2NaHSO_(3)+CO_(2)` Like `CO_(2)` it truns lime water milky due to the formation of insoulble `CaSO_(3)` .However ,if `SO_(2)` is passed for a long time,milkness disappears due to the formation of soluble calcium bisulphite. `Ca(OH)_(2)+SO_(2)rarr underset("Milkness")(CaSO_(3))+H_(2)O` `CaSO_(3)+H_(2)O+SO_(2) underset("soluble")(Ca(HSO_(3))_(2))` |
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| 328. |
Which of the following species decomposes easily?A. `Pb(CH_(3)CO_(2))_(4)`B. `PbCl_(4)`C. `PbI_(4)`D. `PbI_(2)` |
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Answer» Correct Answer - C `PbI_(4)` is not known, probably because of the oxidizing power of `Pb(+4)` and the reducing power of `I^(-)`, which results in `PbI_(2)` always being formed: `PbI_(4) rarr PbI_(2) + I_(2)` `Pb(CH_(3)CO_(2))_(4)` is the only stable lead `+4` oxosalt. |
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| 329. |
Sulphur dioxide decomposes at `1200^(@)C` producingA. `S` and `O_(2)`B. `S` and `O_(3)`C. `SO_(3)` and `S`D. `SO_(3), S` and `O` |
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Answer» Correct Answer - 3 `3SO_(2)rarr2SO_(3)+S` |
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| 330. |
Carbon dioxide is a/an_____oxide.A. neutralB. basicC. acidicD. amphoteric |
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Answer» Correct Answer - C Unlike `CO, CO_(2)` is an acidic oxide. It is the acid anhydride of carbonic acid. Because it is an acid oxide, `CO_(2)` reacts with bases to give carbonates: `2KOH(aq.) + CO_(2)(g) rarr K_(2)CO_(3)(aq.) + H_(2)O(l)` `Ca(OH)_(2)(aq.) + CO_(2)(g) rarr CaCO_(3)(s) + H_(2)O(l)` The presence of excess `CO_(2)` results in the formation of hydrogen carbonates of the alkali and alkaline earth elements: `K_(2)CO_(3)(aq.) + CO_(2)(g) rarr 2KHCO_(3)(aq.) + H_(2)O(l)` `CaCO_(3)(s) + H_(2)O(l) + CO_(2)(g) rarr Ca(HCO_(3))_(2)(aq.)` The second reaction just above accounts for the formation of temporarily hard water. |
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| 331. |
Which of the following systems helps to maintain the `pH` of blood?A. `CO_(2)(aq.)//H_(2)CO_(3)(aq.)`B. `H_(2)CO_(3)(aq.)//HCO_(3)^(-)(aq.)`C. `HCO_(3)^(-)(aq.)//CO_(3)^(2-)(aq.)`D. `H_(2)CO_(3)(aq.)//CO_(3)^(2-)(aq.)` |
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Answer» Correct Answer - B `H_(2)CO_(3)//HCO_(3)^(-)` buffer system helps to maintain the `pH` of blood between `7.26` to `7.42`. |
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| 332. |
Which of the following statements is wrong?A. the bond angle in `H_(2)S` is `92^(@)`B. `H_(2)S` behaves both as an oxidizing as well as a reducing agentC. `H_(2)S` is a diprotic acidD. `H_(2)S` is a stronger acid than `H_(2)O` |
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Answer» Correct Answer - 2 Hydrogen sulphide is a powerful redcuing agent because it can readily given up its hydrogen and deposit sulphur. Thus it burns with a blue flame to form sulphur which is oxidized to sulpher dioxide,i.e, the products depend upon how much oxygen is available : In a limited supply of air or oxygen: `2H_(2)S(g)+O_(2)(g)rarr2H_(2)O(l)+2S(s)` With excess of air and oxygen: `2H_(2)S(g)+3O_(2)(g)rarr2H_(2)O(l)+3SO_(2)(g)` It also reacts with dissolved oxygen in water so that a saturated solution of hydrogen sulphide will slowly go cloudy after standing for some days: `2H_(2)S(aq.)+O_(2)(g)rarr2H_(2)O(l)+2S(s)` Other reducing reactions of hydrogen sulphide included the conversion of (i) moist chlorine to hydrogen chloride: `H_(2)S(g)+underset("moist")(Cl_(2)(g))rarr2HCl(g)+S(s)` (ii) mosist solution dioxide to sulpher: `2H_(2)S(g)+underset("mosit")(SO_(2)(g))rarr2H_(2)O(l)+3S(s)` (iii) sulphuric acid to sulpher dioxide `H_(2)SO_(4)(l)+H_(2)S(g) rarr SO_(2)(g)+2H_(2)O(l)+S(s)` (iv) ferric ions to ferrous ions: `2Fe^(3+)(aq.)+H_(2)S(g) rarr 2Fe^(2+)(aq)+2H^(+)(aq)+S(s)` (v) acidified dichromate to chromium (III) ions: `Cr_(2)O_(7)^(2-) (aq.)+8H^(+)(aq.)+3H_(2)S(g)rarr2Cr^(3+)(aq.)+7H_(2)O(l)+3S(s)` (vi) acidified permanganent to manganous ion `2MnO_(4)^(-) (aq.) +6H^(+)(aq) +5H_(2)S(g)rarr2Mn^(2+) (aq.)+ 8H_(2)O(l) +5S(s)` Note that in the reaction above the hydrogen sulphide is always oxidized to sulpher. The occurrence of sulphur is in volcanic regions is attributed to the `2^(nd)` reaction as both are present in volcanic gases. Other example: (vii) nitric acid is reduced to nitrogen dioxide: `2HNO_(3)rarrH_(2)O+2NO_(2)+O` `H_(2)S+OrarrH_(2)O+S` `2HNO_(3)+H_(2)Srarr2NO_(2)+S+2H_(2)O` (viii) ozone is reduced to dioxygen `H_(2)S+O_(3)rarrH_(2)O+S+O_(2)` (ix) hydrogen peroxide is reduced to water `H_(2)O_(2)+H_(2)Srarr2H_(2)O+S` |
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| 333. |
Plastic or `chi-`sulphur is obtained by pouring liquid sulphur intoA. waterB. ethanolC. `CS_(2)`D. benzene |
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Answer» Correct Answer - 1 Refering to the previous question, as the temperature increases towards the boiling point sulphur (`444^(@)C`) the viscosity slowly drops as the polymer units start to fragment as a result of the greater thermal motion. If this liquid is poured into cold water ,a brown transparent rubbery solid called plastic sulphur is formed.This material slowly changes to microcrystals of rhombic sulphur. Several other forms can be produced by quenching molten S. These may b rfibrous ,laminar ,or rubber -like and a commercial form is called crystex, these are all metastable ,and revert to the `alpha` (cyclo-`S_(8)`) from on standing .Their structures contain spiral chains and sometimes `S_(8)` and others rings. |
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| 334. |
Which of the following orders is incorret?A. `H_(2)O gt H_(2)S gt H_(2)Se gt H_(2)Te` (thermal stability)B. `H_(2)Olt H_(2)S lt H_(2)Se lt H_(2)Te` (acidic stability)C. `H_(2)Te gt H_(2)O gt H_(2)S gt H_(2)Se` (boiling point)D. `H_(2)O gt H_(2)S gt H_(2)Se gt H_(2)Te` (dipole stability) |
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Answer» Correct Answer - 3 Correct order of nitrogen dioxide point is `H_(2)O(373 K) gt H_(2)Te (269K) gt H_(2)Se(232K) gt H_(2)S(213K)` Water has the hightedt boiling point on account of strong intermolecular H-bonding. Thus order of volatility is `H_(2)O lt H_(2)Te lt H_(2)S lt H_(2)S`. Acidic character of the hydrides increases from `H_(2)O` to `H_(2)Te`. The increase in acidic character can be explained in terms of decrease in bond `(H-E)` dissociation enthalpy down the group. Owing to the decrease in ond `(H-E)` dissocaition enthalpy down the group,the thermal stability of hydrides also decreases from `H_(2)O` to `H_(2)Te`. All the hydride except water possess reducing property and this character increases from `H_(2)S` to `H_(2)Te` |
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| 335. |
Which of the following sulphides is soluble in water?A. `As_(2)S_(3)`B. `Sb_(2)S_(3)`C. `CuFeS_(2)`D. `Al_(2)S_(3)` |
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Answer» Correct Answer - 4 Only Group `1` and `2` metals and aluminimum from soluble sulphides. These readily hydrolyze in water, and as a result ,solution of sulphides are very basic: `S^(2-)(aq.)+H_(2)O(l) hArr HS^(-) (aq.)+OH^(-)(aq.)` These is enough hydrolysis of the hydrogen sulphide ,in turn , to give the solution a strong odour of hydrogen sulphide: `HS^(-)(aq.)+H_(2)O(l) hArr H_(2)S(g)+OH^(-) (aq.)` All other metal sulphides are very insoluble. |
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| 336. |
How is `SO_(2)` an air pollutant ? |
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Answer» (i) Sulphur dioxide released in the atmosphere during the combustion of fuels combines with `H_(2)O` molecules and oxygen present to form sulphuric acid. The acid being posonous in `SO_(2)+1//2O_(2)+H_(2)O to H_(2)SO_(4)` nature causes pollution. It causes the corrosion of statues and monuments made from marble `(CaCO_(3))` due to the formation of sulphate. `CaCO_(3)+H_(2)SO_(4) to CaSO_(4)+H_(2)O+CO_(2)` (ii) Sulphur dioxide adversely affects respiratory tract due to its poisonous as well as irritating nature. It causes throat infection as well as irritation in the eyes. (iii) Even very low concentration of the gas (0.03 ppm) has a very damaging effect on plants and vegetation. This is called chlorosis. It slows down the formation of chlorophyll and the leaves slowly wither. |
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| 337. |
Which of the following is incorrect ?A. During the fractional distillation of liquids air the components coming or first is `O_(2)`B. Liquid oxygen is an oxidizer in rockets and misslesC. Dioxygen can be obtained form bleaching powered by heating with a cobalt salt.D. `O_(2)^(+)` is called the dioxygenyl ion |
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Answer» Correct Answer - 1 Since `O_(2)` has higher b.p.than `N_(2)` ,liquids `O_(2)(b.p90K)` is left behind while liquids `N_(2)(b.pt.77K)` is distilled first . `2CaOCl overset(CO^(2+))rarr2CaCl_(2)+O_(2)` |
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| 338. |
Which of the following is not a compound oxide?A. `Pb_(3)O_(4)`B. `Al_(2)O_(3)`C. `Fe_(3)O_(4)`D. `Mn_(3)O_(4)` |
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Answer» Correct Answer - 2 Compound oxides may be regarded as composed of two simplar oxides,the properties of which they usually show, `PbO_(3)O_(4)` is equivalent to `2PbO.PbO_(2)` `Fe_(3)O_(4)"____"` do `Fe_(2)O_(3).FeO` `Mn_(3)O_(4)"_______"` do `"_______"MnO_(2).2MnO` `Pb_(3)O_(4)+4HNO_(3)rarr2Pb(NO_(3))_(2)+PbO_(2)downarrow+2H_(2)O` |
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| 339. |
Which of the following is not a true peroxide?A. `BaO_(2)`B. `MnO_(2)`C. `PbO_(2)`D. Both (2) and (3) |
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Answer» Correct Answer - 4 They are dioxides.There are covalent matallic oxides which decompose when heated giving the basic oxide and oxygen.`(2PbO_(2)rarr2PbO+O_(2))`.They are oxidizing agents but they do not yield hydrogen peroxide solution when acidified and therefore should not be called peroxides. They evolve `Cl_(2)` with conc. `HCl` and `O_(2)` with conc `H_(2)SO_(4)` `MnO_(2)+4HClrarrMnCl_(2)+2H_(2)O+Cl_(2)uparrow` `MnO_(2)+2H_(2)SO_(4)rarr2MnSO_(4)+O_(2)+2H_(2)O` On the other hand ,`BaO_(2)`is a peroxide like`Na_(2)O_(3)`.These ionic compounds contain the peroxide ion`(O-O)^(2-)`.They all give hydrogen peroxide solution when treated with dilute acids: `Na_(2)O_(2)+H_(2)SO_(4)rarrNa_(2)SO_(4)+H_(2)O_(2)` |
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| 340. |
Which of the following oxides is not a mixed anhydride?A. `NO_(2)`B. `P_(4)O_(8)`C. Both (1)and (2)D. `N_(2)O_(3)` |
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Answer» Correct Answer - 4 They are all acidic oxygen which dissolve in water to from oxyacids,hence they are also called acid anhydrides of corresponding acids. `N_(2)O_(3)+H_(2)Orarr2HNO_(2)` `2NO_(2)+H_(2)OrarrHNO_(2)+HNO_(3)` `P_(4)O_(8)+H_(2)Orarr2H_(3)PO_(3)+2H_(3)PO_(4)` Last two oxides which form two oxyacids are called mixed anhydrides. Acidic oxides combines with bases to form salts and water but with basic oxides they form salts only. |
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| 341. |
Which of the following oxides of nitrogen is known as laughing gas?A. Dinnitrogen trioxideB. Dinitrogen oxideC. Dinitrogen monoxideD. Dinitrogen tetroxide |
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Answer» Correct Answer - 2 When inhaled in moderate quantity,`N_(2)O` produces hysterical laughter, hence named as laughing gas. However, when inhaled for long, it produces insensibility and may prove fatal too. Nitrous oxide `(N_(2)O)` is nontoxic in small amounts but all the other nitrogen oxides are highly toxic. |
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| 342. |
All the oxides of nitrogen exhibits (between `N` and `O`)A. `d_(pi) -d_(pi)` bondingB. `p_(pi) -d_(pi)` bondingC. `p_(pi)-p_(pi)` bondingD. `d_(pi)-p_(pi)` bonding |
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Answer» Correct Answer - 3 On account of small size, N is able to exhibit strong `ppi-ppi` multiple bonding in its oxides. Thus, these oxide have open structures and exit usually as monomers. |
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| 343. |
Which of the following oxides of very reactive?A. `NO`B. `N_(2)O`C. `N_(2)O_(4)`D. None of these |
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Answer» Correct Answer - 1 Nitrogen monoxide does show a high reactivity toward dioxygen. It reacts instantly with `O_(2)` i,e, once a sample of colourless `NO` is opend to air brown clouds of `NO_(2)` forms: `2NO(g) +O_(2)(g) hArr 2NO_(2)(g)` It reacts with the halogens to give nitrosyl halides: `2NO(g) +Cl_(2)(g) hArr 2NOCl` |
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| 344. |
Statement 1: Molecular nitrogen is less reactive than molecular oxygen Statement 2: The bond length of `N_(2)` is less as compared to that of `O_(2).`A. If both assertion and reason are correct and reason is correct explanation for assertion.B. If both assertion and reason are correct but reason is not correct explanation for assertion.C. If assertion is correct but reason is incorrect.D. If both assertion and reason are incorrect. |
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Answer» Correct Answer - A Reason is the correct explanation for assertion. |
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| 345. |
Match the column I with column II and mark the appropriate choice. A. `(A) rarr (i), (B) rarr (ii), (C) rarr (iii), (D) rarr (iv)`B. `(A) rarr (iv), (B) rarr (i), (C) rarr (ii), (D) rarr (iii)`C. `(A) rarr (ii), (B) rarr (iii), (C) rarr (iv), (D) rarr (i)`D. `(A) rarr (iii), (B) rarr (iv), (C) rarr (i), (D) rarr (ii)` |
| Answer» Correct Answer - C | |
| 346. |
Which of the following is a tetrabasic acid?A. Hypophosphorous acidB. Metaphosphoric acidC. Pyrophosphoric acidD. Orthophosphoric acid |
| Answer» Correct Answer - C | |
| 347. |
Match the column I with column II and mark the appropriate choice. A. `(A) rarr (iii), (B) rarr (i), (C) rarr (iv), (D) rarr (ii)`B. `(A) rarr (i), (B) rarr (ii), (C) rarr (iii), (D) rarr (iv)`C. `(A) rarr (ii), (B) rarr (iv), (C) rarr (iii), (D) rarr (i)`D. `(A) rarr (iii), (B) rarr (ii), (C) rarr (i), (D) rarr (iii)` |
| Answer» Correct Answer - D | |
| 348. |
Statement-1: In `CO_(2)` molecule resonance is possible. Statement-2: CO is used in purification of Ni. Statement-3: `H_(2)CO_(3)` is more acidic than `H_(2)SiO_(3)`.A. TTTB. TFTC. FFTD. FTF |
| Answer» Correct Answer - A | |
| 349. |
Suggest a reason as to why `CO` is poisonous. |
| Answer» Carbon monoxide is highly-poisonous because of its ability to form a complex with haemoglobin. The CO–Hb complex is more stable than the `O_(2)–Hb` complex. The former prevents Hb from binding with oxygen. Thus, a person dies because of suffocation on not receiving oxygen. It is found that the CO–Hb complex is about 300 times more stable than the `O_(2)–Hb` complex. | |
| 350. |
Is nitrogen gas poisonous in nature ? |
| Answer» Correct Answer - No | |