InterviewSolution
Saved Bookmarks
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.
| 201. |
Assertion : Fluorine combines with sulphur to form `SF_(6)` but no other halogen forms hexahalide with sulphur. Reason : The reactivity of halogens increases as the atomic number increases.A. If both assertion and reason are true and reason is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
|
Answer» Correct Answer - C The reactivity of halogens decreases as the atomic number increases. |
|
| 202. |
Assertion : Fluorine oxidises water to oxygen whereas chlorine and bromine react with water to form corresponding hydrohalic and hypohalous acids. Reason : The reactivity of halogens increases down the group.A. If both assertion and reason are true and reason is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
|
Answer» Correct Answer - C The reactivity of halogens decreases down the group. |
|
| 203. |
The type of hybrid orbitals used by chlorine atom in `ClO_(2)^(-)` is :A. `sp^(3)`B. `sp^(2)`C. spD. None of these. |
|
Answer» Correct Answer - A `H=1//2[7+0-0+1]=8//2=4(sp^(3))` |
|
| 204. |
Assertion: `HClO_(4)` is a stronger acid than `HClO_(3)`. Reason: Oxidation state of `Cl` in `HClO_(4)` is `+VII` and in `HClO_(3)+V`.A. If both assertion and reason are true and reason is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
| Answer» Correct Answer - B | |
| 205. |
Assertion: `HClO_(4)` is a stronger acid than `HClO_(3)`. Reason: Oxidation state of `Cl` in `HClO_(4)` is `+VII` and in `HClO_(3)+V`. |
| Answer» `HClO_(4)` has lower `pK_(a)` value (stronger acid) than `HClO_(3)` (weaker acid). | |
| 206. |
Assertion: `HClO_(4)` is a stronger acid than `HClO_(3)`. Reason: Oxidation state of `Cl` in `HClO_(4)` is `+VII` and in `HClO_(3)+V`.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. |
|
Answer» Correct Answer - B Correct explanation : Greater the number of electronegative atoms present in the oxo-acid, stronger will be the acidic character. |
|
| 207. |
Give one method for industrial preparation and one for laboratory preparation of `CO` and `CO_(2)` each. |
|
Answer» Caron dioxide In the laboratory, `CO_(2)` can be prepared by the action of dilute hydrochloric acid on calcium carbonate. The reaction involved is as follows: `CaCO_(3)+2HCl_((aq))rarrCaCl_(2(aq))+CO_(2(g))+H_(2)O_((i))` `CO_(2)` is commercially prepared by heating limestone. The reaction involved is as follows: `CaCO_(3)overset(Delta)rarrCaO+CO_(2)uarr` Caron monoxide In the laboratory, CO is prepared by the dehydration of formic acid with conc. `H_(2)SO_(4)`, at 373 K. The reaction involved is as follows: `HCOOHoverset("373K")underset("conc". H_(2)SO_(4))rarrH_(2)O+COuarr` CO is commercially prepared by passing steam over hot coke. The reaction involved is as follows: `C_((s))+H_(2)O_((g))overset(473-1273K)rarrunderset("water gas")ubrace(CO_((g))+H_(2(g))` |
|
| 208. |
Nitrogen is relatively inactive element becauseA. its atoms has a stable electronic configurationB. it has low atomic radiusC. its electronegativity is fairly highD. dissociation energy of its molecule is fairly high. |
|
Answer» Correct Answer - D `N_(2)` molecule contains triple bond between N atoms, having very high dissociation energy `(946 kJ mol^(-1))` due to which it is relatively inactive. |
|
| 209. |
Assertion : The basicity of hypophorus acid is two. Reason : Two hydrogen atoms are bonded to phosphorus atoms.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. |
|
Answer» Correct Answer - A Reason is the correct explanation for assertion. |
|
| 210. |
What is the nature of the following oxides : (i) `CO (ii) Al_(2)O_(3) (iii) CO_(2) (iv) CaO (v) SO_(3)` ? |
| Answer» (i) neutral (ii) amphoteric (iii) acidic (iv) basic (v) acidic | |
| 211. |
What happends when water is dropped over `Na_(2)O_(2)` ? |
| Answer» Correct Answer - `O_(2)` is evolved | |
| 212. |
`Br_(2)+NaI to ` |
| Answer» `Br_(2)+2NaI to 2NaBr+I_(2)` | |
| 213. |
`NH_(4)Cl(aq)+NaNO_(2)(aq) overset("heat") to` |
| Answer» `NH_(4)Cl(aq)+NaNO_(2)(aq) overset("heat") to NaCl(aq) +N_(2)(g) +2H_(2)O(aq)` | |
| 214. |
Which of the following combinations is used to prepare nitric acid in the laboratory?A. `NaNO_(3)` and conc. `H_(2)SO_(4)`B. `N_(2)` and `O_(2)`C. `NH_(3)` and `O_(2)`D. `NaNO_(2)` and conc. `H_(2)SO_(4)` |
|
Answer» Correct Answer - 1 `HNO_(3)` was named aqua fortis (meaning strong water ) by alchemists. Glauber obtained it by the action of sulphuric acid on nitre. It is prepared in the laboratory by distilling sodium or potassium nitrate with concentrated sulphuric acid in a glass retort `NaNO_(3)+H_(2)SO_(4)rarrNaHSO_(4)+HNO_(3)` The vapout of nitric acid are condensed in a glass receiver. The nitric acis so obtained may contain oxides of nitrogen as impurity. The dissolved oxides of nitrogen are removed by redistillation or blowing a current of `CO_(2)` through warm acid. |
|
| 215. |
Which of the following is incorrect for nitrogen pentoxide?A. In the gas phase, `N_(2)O_(5)` decomposes with explosion into `NO, NO_(2)` and `O_(2)`B. It reacts with concentrated `H_(2)SO_(4)` to produce `NO_(2)^(+)`C. It is relatively inertD. It acts as a strong oxidising agent |
|
Answer» Correct Answer - 3 it is highly reactive. It affects organic substances such as cork, rubber ect. It oxidises iodine readily into iodine pentoxide: `I_(2)+5N_(2)O_(5)rarrI_(2)O_(5)+10NO_(2)` `N_(2)O_(5)+3H_(2)SO_(4)rarrH_(3)O^(+)+2NO_(2)^(+)+3HSO_(4)^(-)` |
|
| 216. |
What happens when mixture of `NH_(3)` and air is passed over heated platinum gauze ? |
| Answer» Correct Answer - Oxygen is evolved | |
| 217. |
When borax is dissolved in waterA. both `B(OH)_(3)` and `[B(OH)_(4)]^(-)`B. only `B(OH)_(3)` is formedC. only `[B(OH)_(4)]^(-)` is formedD. None of these. |
|
Answer» Correct Answer - A `[B_(4)O_(5)(OH)_(4)]^(2) + 5H_(2)O rarr 2B(OH)_(3) + 2[B(OH)_(4)]^(-)` ltbtgt This confirms that borax is made up of two triangular `BO_(3)` units and two tetrahedral `BO_(4)` units. When borax is used for titrating against acids, only `[B(OH)_(4)]^(-)` reacts with `HCl` : `2[B(OH)_(4)]^(-) + 2H_(3)O^(+) rarr 2B(OH)_(3) + 4H_(2)O` |
|
| 218. |
What was the reason applied by Bartlett for carrying out the reaction of xenon with `PtF_(6)` ? |
| Answer» `PtF_(6)` can cause of ionisation of xenon having least ionisation enthalpy among noble gas elements. | |
| 219. |
How are `XeF_(2) " and " XeF_(4)` prepared ? Give their structures and also mention the state of hybridisation involved. |
| Answer» `XeF_(2)(sp^(3)d),XeF_(4) (sp^(3)d^(2))` | |
| 220. |
Why elements of group 18 known as noble gases? |
| Answer» Elements of group 18 have valence shell orbitals, completely filled and therefore react with few elements only under certain conditions. | |
| 221. |
Nitrozen (i) oxide is produced byA. thermal decomposition of ammonium nitrateB. disproportionation of `N_(2)O_(4)`C. thermal decomposition of ammonium nitriteD. interaction of hydroxyl amine and nitrous acid. |
|
Answer» Correct Answer - A::D `NH_(4)NO_(3) overset("heat")to N_(2)O+2H_(2)O` `NH_(2)OH+HONO to N_(2)O+2H_(2)O` |
|
| 222. |
Statement I Nitrogen and oxygen are the main components in the atmosphere but these do not react to form oxides of nitrogen. Statement II The reaction between nitrogen and oxygen requires high temperature.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. |
|
Answer» Correct Answer - A Reason is the correct explanation for assertion. |
|
| 223. |
In which of the following pairs , both the species are not isostractural ?A. `NH_(3), PH_(3)`B. `XeF_(4), XeO_(4)`C. `SiCl_(4), PCl_(4)^(+)`D. Diamond, silicon carbide |
|
Answer» Correct Answer - 2 `XeF_(4)implies` [steric number `=4`atoms +`2` lone pairs ]`implies` Geometery is octahdral but shape is square planar `XeO_(4)implies`[Steric number=`4`atoms +`0`lone pair]`implies`Geometery as well as shape is tetrahedral (1) Both `NH_(3)` and `PH_(3)` (Steric number :`3+1=4`) are trigonal pyramidal in shape (2) Both `SiCl_(4)` and `PCl_(4)^(+)` (Steric number : `4+0=4`) are tetrahedral in shape ` (3) Both diamond and `SiC` are network covalent solids with identical crystal lattice where every atom is covalently bonded to four other atoms oriented tetrahedrally. |
|
| 224. |
Decreasing order of stability of `O_(2), O_(2)^(-), O_(2)^(+)` and `O_(2)^(2-)` isA. `O_(2) gt O_(2)^(+) gt O_(2)^(-) gt O_(2)^(-)`B. `O_(2)^(-) gt O_(2)^(2-) gt O_(2)^(+) gt O_(2)`C. `O_(2)^(+) gt O_(2) gt O_(2)^(-) gt O_(2)^(2-)`D. `O_(2)^(2-) gt O_(2)^(-) gt O_(2) gt O_(2)^(+)` |
|
Answer» Correct Answer - 3 Stability of `alpha` Bond order i.e, higher to bond order ,greater the stability. According to `MOT` Bond order `=(1)/(2)[N_(b)-N_(a)]` `O_(2)`: Bond order `implies(1)/(2)[10-6]=2` `O_(2)^(-)`: Bond order `implies(1)/(2)[10-7]=1.5` `O_(2)^(+)`: Bond order :` rArr (1)/(2)[10-5]=2.5` `O_(2)^(2-)`: Bond order `implies(1)/(2)[10-8]=1.0` Thus, desreasing order of stability is `O_(2)^(+) gt O_(2) O_(2)^(-) gt O_(2)^(2-)` |
|
| 225. |
Which of the following acids forms three series of salts?A. `H_(3)PO_(2)`B. `H_(3)BO_(3)`C. `H_(3)PO_(4)`D. `H_(3)PO_(3)` |
|
Answer» Correct Answer - C `H_(3)PO_(4)` is a tribasic acid as it has 3P-OH bonds i.e., 3 ionisable H atoms thus, can form three series of salts. |
|
| 226. |
Strong reducing behaviour of `H_(3)PO_(2)` is due toA. low oxidation state of phosphorusB. presence of two - OH groups and one P-H bondC. presence of one - OH group and two P-H bondsD. high electron gain enthalpy of phosphorus. |
|
Answer» Correct Answer - C `H_(3)PO_(2)` behaves as a stronger reducing agent as it contains two P-H bonds. |
|
| 227. |
Strong reducing behaviour of `H_(3)PO_(4)` is due to :A. High oxidation state of phosphorusB. Presence of two`-OH` group and one `P-H` bondC. Presence of one `-OH` group and two `P-H` bondD. High electron gain enthalpy of phosphorus |
|
Answer» Correct Answer - 3 Acids which contain `P-H` bond have strong reducing properties .For example ,hypophosphorous acid `(H_(3)PO_(2))` is a good reducing agent as it contains two `P-H` bonds and thus reduces `AgNO_(3)` to metallic `Ag` and `HgCl_(2)` to `Hg` `4AgNO_(3)+H_(3)PO_(2)+2H_(2)Orarr4Agdownarrow+H_(3)PO_(4)+4HNO_(3)` `2HgCl_(2)+H_(3)PO_(2)+2H_(2)Orarr2Hg+H_(3)PO_(4)+4HCl` ti also reduces arenediazonium sales to arenes: `2C_(6)H_(5)N_(2)Cl+H_(3)PO_(2)+2H_(2)Orarr2C_(6)H_(6)+H_(3)PO_(4)+2N_(2)+2HCl` |
|
| 228. |
Which of the following is not an amphoteric oxide?A. `PbO_(2)`B. `PbO`C. `BeO`D. `BaO` |
|
Answer» Correct Answer - 4 `BaO` is a basic oxide ,Basic oxides either dissolve in water to form alkalies or combine with acids to from salts and water or combine with acidic ocide to form salts. `BaO+2HCl-.BaCl_(2)+H_(2)O` The rest of the oxides are amphoteric oxides are `PbO + H_(2)SO_(4) rarr PbSO_(4)+H_(2)O` `PbO +2NaOH rarr Na_(2)PbO_(2)+H_(2)O` Other examples of amphoteric oxides are `ZnO,Al_(2)O_(3),Sb_(2)O_(3),Cr_(2)O_(3)` `ZnO+2HClrarrZnCl_(2)+H_(2)O` `ZnO+2NaOHrarrNa_(2)ZnO_(2)+H_(2)O` `Cr_(2)O_(3)+3H_(2)SO_(4)rarrCr_(2)(SO_(4))_(3)+3H_(2)O` `Cr_(2)O_(3)+2NaOH rarr Na_(2)Cr_(2)O_(4)+H_(2)O` |
|
| 229. |
Which of the following is not a neutral oxide?A. `Al_(2)O_(3)`B. `CO`C. `N_(2)O`D. `NO` |
|
Answer» Correct Answer - 1 There are some oxides which are neither acidic nor basic. Such oxides which neither combine with acids nor with bases to form salts are known as netural oxides. examples are `CO,NO`,and `N_(2)O`.On the other hand ,`Al_(2)O_(3)` ,is an amphoteric oxide as it reacts with acids as well as bases. `Al_(2)O_(3)(s)+6HCl(aq)+9H_(2)O(l)rarr2[Al(H_(2)O)_(6)]^(2+)(aq.)=6Cl^(-)(aq.)` `Al_(2)O_(3)(s)+6NaOH(aq.)+3H_(2)O(l)rarr2Na_(3)[Al(OH)_(6)](aq.)` |
|
| 230. |
Which of the following is a neutral oxide?A. `CO`B. `GeO`C. `SnO`D. `PbO` |
|
Answer» Correct Answer - A It is a neutral oxide since it does not react with water to produce an acid or a base. `GeO` is distinctly acidic, whilst `SnO` and `PbO` are amphoteric. |
|
| 231. |
Which of the following Group 15 elements can form a neutral oxide?A. NitrogenB. PhosphorusC. Arsenic and antimonyD. Bismuth |
|
Answer» Correct Answer - 1 Nitrogen is the only Group `15` element that forms neutral oxides such as nitrous oxide `(N_(2)O)` and nitric oxide `(NO)`. |
|
| 232. |
Xenon does not form fluorides such as `XeF_(3)` and `XeF_(5)`. Explain. |
| Answer» We know that all the occupied orbitals in xenon atom are paired. By the promotion of one, two or three electrons from the filled p-orbitals to the vacant d-orbitals in the valence shell, two, four or six half filled orbitals are formed. Thus, xenon can combine only with even number of fluorine atoms and not odd. In other words, it cannot form compounds like `XeF_(3)` and `XeF_(5)`. | |
| 233. |
How are xenon fluorides `XeF_(2)`, `XeF_(4)` and `XeF_(6)` obtained? |
|
Answer» `XeF_(2)`, `XeF_(4)`, and `XeF_(6)` are obtained by a direct reaction between `Xe` and `F_(2)`. The condition under which the reaction is carried out determines the product. `underset(("Excess"))(Xe_((g))) + F_(2(g))overset("673K, 1bar")to XeF_(2(s))` `underset(("1 : 5 ratio"))(Xe_((g))) + 2F_(2(g))overset("873K, 7bar")to XeF_(4(s))` `underset(("1 : 20 ratio"))(Xe_((g))) + 3F_(2(g))overset("573K,60-70bar")to XeF_(6(s))` |
|
| 234. |
Which of the xenon fluorides ndergoes disproportionation during the hydrolysisA. `XeF_(2)`B. `XeF_(4)`C. `XeF_(6)`D. All of these |
|
Answer» Correct Answer - 2 Hydrolysis of `XeF_(4) (O.N." of "Xe" is "(+4))` gives `Xe (O.N" is "O)` and `XeO_(3) (O.N." is "+6)`: `6XeF_(4)+12H_(2)Orarr4Xe+2XeO_(3)+24HF+3O_(2)` `XeF_(2)` is hydrolysed to give `Xe, He`, and `O_(2)` ` 2XeF_(2)(s)+2H_(2)O(l)rarr2Xe(g)+4HF(aq.)+O_(2)(g)` Complete hydrolysis of `XeF_(6)` with water gives `XeO_(3)`: `6XeF_(4)+12H_(2)O rarr 4He+2XeO_(3) +24HF+3O_(2)` Partial hydrolysis of `XeF_(6)` gives oxyfluroides `XeOF_(4)` and `XeO_(2)F_(2)`: `XeF_(6)+H_(2)OrarrXeOF_(4)+2HF` `XeF_(6)+2H_(2)Orarr XeO_(2)F_(2)+4HF` |
|
| 235. |
Xenon fluorides are all extermely strongA. reducing agentB. oxidizing agentC. flourinating agentsD. both (2) and (3) |
|
Answer» Correct Answer - 4 They are all extremely strong oxidizing and fluorinating agents. They react quantitatively with hydrogen as follows: `XeF_(2)+H_(2)rarr2HF+Xe` `XeF_(4)+2H_(2)rarr4HF+Xe` `XeF_(6)+3H rarr 6HF+Xe` They oxidizes chloride to chlorine iodide to cerium `(+3)` to cerium `(+4)`: `XeF_(2)+2HCl rarr Cl_(2)+2HF+Xe` `XeF_(4)+4Kl rarr 2I_(2)+4KF+Xe` `SO_(4)^(2-)+XeF_(2)+Ce_(2)(SO_(4))_(4)rarr2Ce(SO_(4))_(2)+F_(2)+Xe` They fluorinate compounds: `XeF_(4)+C_(6)H_(6)rarrC_(6)H_(5)F+Xe+HF` `XeF_(4)+Pt rarr PtF_(4)+Xe` `XeF_(4)+2SF_(4)rarr2SF_(6)+Xe` |
|
| 236. |
Structure of xenon fluorides cannot be explained by valence bond theory. Explain. |
| Answer» According to valence bond theory, only the unpaired electrons present in the valence shell of an atom can participate in covalent bond formation. However, the element xenon and all other noble gas elements donot have any unpaired electrons present in their atoms. They are not expected to form any bonds according to the theory. | |
| 237. |
which of the following statement is not correct ?A. all the group `15` element form two types of oxides: `E_(2)O_(3)` and `E_(2)O_(5)`B. The oxide in the higher oxidation state of the element is mor acidic than that of lower oxidation stateC. Acidic character of oxides increases on moving down the groupD. Oxides of P, As, Sb and Bi exist as the dimmers. |
|
Answer» Correct Answer - 3 The acids character of the oxides decreases (or the basic nature of the oxides increases) with increasesing atomic number. Thus oxides of the types `E_(2)O_(3)`of `N` and `P` are purely acidic,that of `As` and `Sb`are amphoteric and `Bi(III)`oxide is distinctly basic. `Bi_(2)O_(3)` dissolves in acids to give salt: `Bi_(2)O_(3)+6HNO_(3)rarr2Bi(NO_(3))_(3)+3H_(2)O` Among group `15` elements,`Bi` alone forms a stable nitrate, sulphate or carbonate and thus behave like a metal. The reluctance of `P, As, Sb` and `Bi` to enter into `p pi-p pi` multiple bonding leads to cage structures for their oxides and the exist as the dimers `E_(4)O_(6)` and `E_(4)O_(10)`. Bi (V)oxide is unstabel. |
|
| 238. |
which of the folowing is the strongest oxidizing agent?A. `As_(2)O_(5)`B. `N_(2)O_(5)`C. `P_(2)O_(5)`D. `Sb_(2)O_(5)` |
|
Answer» Correct Answer - 2 Among these oxides `P_(2)O_(5)` is most stable pentoxide (decomposition temperature ` 420^(@)C`) and `N_(2)O_(5)` is least stable (decomposition temperature `30^(@)C)`. As `N_(2)O_(5)` is least stable, it acts as a powerful oxidizing agent due to furnishing of `O_(2)` |
|
| 239. |
which of the following is the weakest base?A. `CH_(3)NH_(2)`B. `NH_(3)`C. `N_(2)H_(4)`D. `NH_(2)OH` |
|
Answer» Correct Answer - 4 On account of electron withdrawing effects of OH group ,hydroxylamine is a weaker base then ammonia or hydrazine. Salts contain the hydroxylammonium ion `[NH_(3)OH]^(+)`. ` NH_(2)OH + HCl rarr [NH_(3)OH]^(+)Cl^(-)` `NH_(2)OH+H_(2)SO_(4)rarr[NH_(3)OH]^(+)HSO_(4)^(-)` |
|
| 240. |
Which of the following is incorrect for ozone ?A. it is a pale blue gas with a characteristics strong smellB. it can be liquified (at`-112.4^(@)C` ) to a dark blue liquid and solified (at `-248^(@)C` ) to yield violet black crystals.C. it is thermodynamically unstableD. it is paramagnetic is nature |
|
Answer» Correct Answer - 4 Unlike `O_(2)` trioxygen `(O_(3))` is diamagnetic .The colour of `O_(3)` is due to intense absorption of red light `(lambda557and602nm)`. It has a characteristic "metallic" smell and in small concentration rises to above about `100` parts per million breathing becomes uncomfortable and it cause headaches. Ozone is thermodynamically unstable and decomposes to `O_(2)`. The decompositions is exothermic and is catalyzed by many materials.The solid and liquid often decompose explosively. The gas decomposes slowly, even when warmed , providing catalysts and `UV` light are absent. |
|
| 241. |
Which of the following has the highest boiling point?A. `SbH_(3)`B. `AsH_(3)`C. `PH_(3)`D. `NH_(3)` |
|
Answer» Correct Answer - 1 The boiling points increases regularly as we move from `PH_(3)` To `BiH_(3)`. However , the boiling point of `NH_(3)` is higher than those of `PH_(3)` and `AsH_(3)` but lower than those of `SbH_(3)` and `BiH_(3)` On account of very high electronegativity of `N` ,ammonia undergoes intermolecular `H`- bonding while other hydrides do not form intermolecular `H-`bonds on account of low electronegativities of central atoms. As we move from `PH_(3)` and `BiH_(3)`, the miolecular mass increases causing a corresponding increase in the strength of the vander Waals forces of attraction. Consequently the boiling point increases regularly from `PH_(3)` to `BiH_(3)` The incresases in the boimg oint of `SbH_(3)` and `BiH_(3)` because of increasing in bpt of `NH_(3)` becasue of `H`-bonding. |
|
| 242. |
Silica reacts with `HF` to produceA. `Si` and `HFO_(2)`B. `SiF_(2)` and `H_(2)O`C. `H_(2)[SiF_(6)]` and `H_(2)O`D. `SiF_(4)` and `H_(2)O` |
|
Answer» Correct Answer - 3 Industrially `MF` is made by heating `CaF_(2)` with concentrated `H_(2)SO_(4)` However, it is important that `SiO_(2)` impurities are removed from the `CaF_(2)`, as otherwise they consume much of the `HF` produced: `SiO_(2)(s)+4HF(aq.)rarrSiF_(4)(g)+2H_(2)O(l)` `SiF_(4)(g)+2HF(aq.)rarrunderset("fluorosilic acid")((H^(+))_(2)SiF_(6)^(2-)(aq.))` |
|
| 243. |
Atomicity of phosphorus isA. oneB. twoC. threeD. four |
| Answer» Correct Answer - D | |
| 244. |
Which of the following is incorrect for `p`-block elements?A. Some of the elements exhibit variable valencies.B. Some of the elements exhibit variable oxidation numbers.C. Lighter elements exhibit inert pair effect.D. The highest oxidation number shown by a `p`-block element is equal to the sum of `ns`- and `np`-electrons in the valence shell. |
|
Answer» Correct Answer - C Inert pair effect is the characteristic of the heaviest elements of `p`-block. |
|
| 245. |
`Cl_(2)+F_(2) ("excess") to` |
| Answer» `Cl_(2)+5F_(2)("excess") to 2ClF_(5)` | |
| 246. |
Write the reactions of `F_(2)` and `Cl_(2)` with water. |
|
Answer» (i) `Cl_(2) + H_(2)O to underset("Hydrochloric acid")(HCl) + underset("Hypochlorous acid")(HOCl)` (ii) `2F_(2(aq)) + 2H_(2)O_((l)) 4H_((aq))^(+) + 4F_((aq))^(-) + O_(2(g)) + 4 HF_((aq))` |
|
| 247. |
Carbon dioxide is prepared by burning_____in excess of air of oxygen.A. carbonB. fossil fuelsC. organic compoundsD. all of these |
|
Answer» Correct Answer - D It is prepared by the complete combustion of carbon and carbon-containing fuels in excess of air: `C(s) + O_(2)(g) rarr CO_(2)(g)` `CH_(4)(g) + 2O_(2)(g) overset(Delta)rarr CO_(2)(g) + 2H_(2)O(g)` |
|
| 248. |
Which of the following reactions is not described correctly?A. `CO(g)+S(s) rarr COS(g)`B. `Fe+9CO underset("under pressure")overset(200^(@)C)rarr Fe(CO)_(9)`C. `CO(g) + Cl_(2)(g) rarr COCl_(2) (g)`D. `2CO(g)+O_(2)(g)rarr 2CO_(2)(g)` |
|
Answer» Correct Answer - B `Fe + 5CO underset("under pressure")overset(200^(@)C)rarr Fe(CO)_(5)` `2Fe(CO)_(5) overset("Photolysis")rarr Fe_(2)(CO)_(9) + CO` Carbon monoxide is quite reactive, it burns with a .blue flame to carbon dioxide. It reacts with `Cl_(2)` gas in the presence of light or hot charcoal, which serve as catalysts, to give carbonyl chloride `(COCl_(2))` which is especially useful as a starting material for the synthesis of polycarbonates that are widely used as tough low - density transparent materials. When carbon monoxide is passed over heated sulphur, the compound carbonyul sulphide `(COS)`, a promising low - hazard fungicide, is formed. |
|
| 249. |
Which of the following formula does not represent a metal carbonyl correctly?A. `Mn_(2)(CO)_(10)`B. (2) `Fe_(2)(CO)_(9)`C. `Cr_(2)(CO)_(6)`D. `Co_(2)(CO)_(8)` |
|
Answer» Correct Answer - C `CO` is an important ligand. It can donate an electron pair to many transition metals, forming carbonyl compounds. The number of `CO` molecules bonded to the metal is generally in accordance with the effective atomic number rule. Carbonyl formed with chromium is actually `Cr(CO)_(6)`. |
|
| 250. |
Carbon monoxide acts as a donor and reacts with certain metals to give carbonyls. This is due toA. presence of one sigma and two pi bonds between C and O `( :C -= O: )`B. presence of a lone pair on carbon atom in CO moleculeC. Presence of lone pair on oxygen atom in CO moleculeD. Poisonous nature of CO |
| Answer» Correct Answer - B | |