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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.
| 151. |
On combustion in excess ofd air, lithium formsA. normal oxidesB. peroxidesC. superoxidesD. both (1) and (2) |
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Answer» Correct Answer - A Li forms mainly the oxide, `Li_(2)O` (plus some peroxide), Na forms the peroxide, `Na_(2)O ("plus some" Na_(2)O)`, whilst K, Rb, and Cs form the superoxides, `MO_(2)`. |
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| 152. |
The pairr of amphoteric oxides isA. `BeO,ZnO`B. `Al_(2)O_(3),Li_(2)O`C. `BeO,BO_(3)`D. `BeO,MgO` |
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Answer» Correct Answer - A BeO and ZnO are amphoteric oxides. |
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| 153. |
Which of the following oxides of group 2 elements is amphoteric ?A. SrOB. BeOC. MgOD. CaO |
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Answer» Correct Answer - B As the atoms becomes larger, the ionization enthalpy decreases and the elements become more basec. BeO is in soluble in water but dissolved in acids to give salts `BeO+HCl toBeCl_(2)+H_(2)O` And in alkalis to give beryllates, which on stading precipitate as hydroxide. `BeO+NaOHtoNa_(2)BeO_(2)+H_(2)O` BeO is, therefore, amphoteric. MgO reacts with water forming `Mg(OH)_(2)` which is extermely insoluble in water and hence weakly basic. CaO Reacts `Ca(OH)_(2)` which is a moderately strong base. `Sr(OH)_(2)` and `Ba(OH)_(2)` are even stronger bases. the reaction of these oxides with water sometimes is known as slaking. |
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| 154. |
Which of the following hydroxides of group 2 elements is amphoteric ?A. `Mg(OH)_(2)`B. `Ca(OH)_(2)`C. `Be(OH)_(2)`D. `Sr(OH)_(2)` |
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Answer» Correct Answer - C the basic strength of metl hydroxides is decided by the ease with which they can release `OH^(-)` ions. As we move down the group the attraction between `M^(2+)` ion and `OH^(-)` ions decreases on account of the decrease of change density of `M^(2+)` ion. therefore, the basic strength of group 2 hydroxides increases on moving down the group. Group 2 hydroxides are less basic than the corresponding group 1 hydroxides bacause `M^(2+)` ios with greater charge density attract `OH^(-)` ions Strongly in comparison to `M^(+)` ions of alkali metals. `Be(OH)_(2)` is insoluble in water but dissolves in acid as well as in solutions containing an excess of `OH^(-)` ions `Be(OH)_(2)+2HCl toBeCl_(2)+2H_(2)O` `Be(OH)_(2)+2NaOHtoNa_(2)BeO_(2).2H_(2)O` or `Na_(2)[Be(OH)_(4)]` or `Be(OH)_(2)+2OH^(-)tounderset("Beryllate ion")([Be(OH)_(4)]^(2-))` `Be(OH)_(2)` is therefore, amphoteric. |
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| 155. |
When a metal of group 1 was dissolved in liquid ammonia, the following observations were obtained (a) Blue solution was obtained initially. On concentrating the solution, blue colour changed to bronze colour.How do you account for the blue colour of the solution? Given the name of the product formed on keeping the solution for some time. |
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Answer» (a) The reaction that takes place when alkali metal is dissolved in liquid ammonia is `M +(x+y)NH_(3) rarr [M(NH_(3))_(x)]^(+)+ [(NH_(3))_(y)]^(-e)` The blue colour of the solution is due to the presence of ammoniated electron which absorb energy in the visible region of light and thus, impart blue colour to the solution. (b) In concentrated solution, the blye colour changes to bronze colour due to the formation of metal ion clusters. The blue solution on keeping for some time liberate hydrogen slowly with the formation of amide. `underset("Ammoniacal")(M^(+)+e^(-))+NH_(3)rarr underset("Amide")(MNH_(2))+(1)/(2)H_(2)` |
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| 156. |
When sodium is dissolved in liquid ammonia, a solution of deep blue colour is obtained. The colour of the solution is due toA. ammoniated electronB. sodium ionC. sodium amideD. ammoniated sodium ion |
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Answer» Correct Answer - A All alkali metal dissolve in liquid `NH_(3)` giving highly conducting deep blue solution. `Na +(x+y) NH_(3) rarr underset("Ammoniated cation")([Na(NH_(3))x]^(+))+underset("Ammoniated electron")(e(NH_(3))_(y)^(-))` When light fall on these solutions, the ammoniated electrons excite in higher energy level by absorbinf red wavelength and so transmitted light is blue. |
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| 157. |
A compound of sodium does not give `CO_(2)` when heated but it gives `CO_(2)` when treated with dilute acids. A crystalline compound is found to have 37.1% Na and 14.52% `H_(2)O`. Hence, compound isA. `NaHCO_(3)*10H_(2)O`B. `NaHCO_(3)*5H_(2)O`C. `Na_(2)CO_(3)*10H_(2)O`D. `Na_(2)CO_(3)*H_(2)O` |
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Answer» Correct Answer - D `CO_(2)` is obatined only when the compound is decomposed by acid thus, it is `Na_(2)CO_(3)`. It cannot be `NaHCO_(3)` since, it given `CO_(2)` on heating. Probable compound is `Na_(2)CO_(3).xH_(2)O` `{:(,,"Molar ratio","Ratio"),(Na_(2)CO_(3),85.48,0.8064,1),(H_(2)O,14.52,0.8064,1):}` Thus, compound is `Na_(2)CO_(3)*H_(2)O` Molecular weight `=124" g "mol^(-1)` percentage of sodium `=(2xx23)/(124)xx100=37.1%` |
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| 158. |
Nuclear attraction is often the deciding control factor for the association of neutral molecules to a given metal ion. Which onee of the following represents the correct order of stability of the ions? `[Be(H_(2)O)_(4)]^(2+),[Mg(H_(2)O)_(4)]^(2+),[Ca(H_(2)O)_(4)]^(2+)` and `[Sr(H_(2)O)_(4)}^(2+)`A. `[Be(H_(2)O_(4)]^(2+) gt [Sr(H_(2)O_(4)]^(2+)gt [Mg(H_(2)O)_(4)]^(2+) gt [Ca(H_(2)O)_(4)]^(2+)`B. `[Ca(H_(2)O)_(4)]^(2+) gt [Mg(H_(2)O)_(4)]^(2+) gt [Be(H_(2)O)_(4)]^(2+) gt gt[S(H_(2)O)_(4)]^(2+)`C. `[Sr(H_(2)O)_(4)]^(2+) gt [Ca(H_(2)O)_(4)]^(2+) gt [Mg(H_(2)O)_(4)]^(2+) gt [Be(H_(2)O)_(4)]^(2+)`D. `[Be(H_(2)O)_(4)]^(2+) gt [Mg(H_(2)O)_(4)]^(2+) gt [Ca(H_(2)O)_(4)]^(2+) gt [Srr(H_(2)O)_(4)]^(2+)` |
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Answer» Correct Answer - D The degree of hydration and the amount of hydration energy decreases as the size of the ion increases from `Be^(2+)` to `Sr^(2+)`. `{:(,Be^(2+)lt,Mg^(2+)lt,Ca^(2+)lt, Sr^(2+)),("Hydration Energy "(kJ" "mol^(-1)),-2494,-1921,-1577,-1443):}` Thus, stability of hydrated ion is `[Be(H_(2)O)_(4)}^(2+) t [Mg(H_(2)O)_(4)]^(2+) gt [Ca(H_(2)O)_(4)]^(2+)gt[Sr(H_(2)O)_(4)]^(2+)` |
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| 159. |
Write the names of alkaline earth metals in increasing order of atomic number. |
| Answer» Beryllium, magnesium, calcium,strontium, barium and radium. | |
| 160. |
The elements of group 1 are called alkali metals because |
| Answer» Hydroxide formed by these metals on reaction with water are strongly alkaline in nature. | |
| 161. |
Which of the following is used in the preparation of mortar, a building material ?A. CaOB. `Ca(OH)_(2)`C. `CaCO_(3)`D. `CaCl_(2)` |
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Answer» Correct Answer - B Mortar is prepared by mixing slaked lime with 3-4 times its weight of sant `(SiO_(2))`. The mixture is made into a thick paste with gradual addition of water. The paste is called mortar and is used in building constructions. It sets into a hard mass by the loss of `H_(2)O` and the gradual absorption of `CO_(2)` from the air. Sometimes coal ash is mixed with lime instead of sand. |
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| 162. |
Baryta water is used for detecting___gas.A. `CO_(2)`B. COC. `NH_(3)`D. `O_(2)` |
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Answer» Correct Answer - A Baryta water is aqueous barium hydroxide. It turns turbid when comes in contact with `CO_(2)` on account of the formation of insoluble |
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| 163. |
Which of the following compounds is used to make prisms and cell windows for spectrophotometres?A. `BeF_(2)`B. `MgF_(2)`C. `CaF_(2)`D. `BaF_(2)` |
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Answer» Correct Answer - C Fluorite (or fluorspar) is a white, insoluble, highmelting solid. It is very important industrially as it is the main source of both `F_(2)` and HF: `CaF_(2)+H_(2)SO_(4)rarr2HF+CaSO_(4)` `HF+KFrarrKHF_(2)overset("Electrolysis")rarrF_(2)` |
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| 164. |
Which compound is formed when lithium reacts directly with nitrogen in air? |
| Answer» Lithium nitride. `Li_(3)N`. | |
| 165. |
Which of the following statement(s) is/are correct?A. KOH is less strong alkali than NaOHB. Milk of magnesia is an aqueous solution of `Mg(OH)_(2)`C. `Mg^(+2)` ions are not precipitated with the addition of `NH_(4)OH` in the presence of `NH_(4)Cl`D. `CaO_(2)` is less stable than `MgO_(2)`. |
| Answer» Correct Answer - B::C | |
| 166. |
The normal oxide contains______ion, peroxide contains_____ion and superoxide contains____ion.A. `O^(2-),O_(2)^(2-),O_(2)^(-)`B. `O^(2-),O_(2)^(-),O_(2)^(2-)`C. `O^(-),O^(2-),O^(3-)`D. `O^(-),O^(2-),O_(2)^(2-)` |
| Answer» Correct Answer - A | |
| 167. |
Which of the following statement is/are correct?A. KCl is a substitute for NaClfor patients of high blood pressureB. KOH is a stronger alkali than NaOHC. KOH is used in the manufacturing of soft soapD. NaOH is a non-deliquescent white crystalline solid |
| Answer» Correct Answer - A::B::C | |
| 168. |
Which of the following statements is/are correct?A. `NaHCO_(3)` is more soluble than `Na_(2)CO_(3)`B. `NaOH` is known as caustic sodaC. `NaHCO_(3)` is used as an antacidD. `Na_(2)CO_(3)` is used in the manufacturing of soap and glass |
| Answer» Correct Answer - B::C::D | |
| 169. |
Superoxide of potassium isA. `K_(2)O`B. `K_(2)O_(2)`C. `KO_(2)`D. `K_(2)O_(3)` |
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Answer» Correct Answer - C In superoxides, the oxidation number of oxygen is -1/2. Thus `K^(+)O_(2)^(-)` is the superoxide of potassium. |
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| 170. |
Potassium iodide act as reducing agent when treated withA. Acidified `K_(2)Cr_(2)O_(7)` solutionB. An acidified `KMnO_(4)` solutionC. A `CuSO_(4)` solutionD. A lead acetate solution |
| Answer» Correct Answer - A::B::C | |
| 171. |
The s- block elements of the periodic table are those in which the last elctron enters the s-subshell of the____ shell.A. penultimateB. antepenultimateC. outermostD. foremost |
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Answer» Correct Answer - C Last electron, also called differentiating electron, enters the s-orbital of the last shell. Thus their general valence shell electron configuration is `ns^(1//2)`. |
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| 172. |
Which of the following oxidation numbers (Ons) are exhibited by the alkali metals ?A. `0 and +1`B. `+1 and +2`C. `only +1`D. `0,+1, and +2` |
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Answer» Correct Answer - A In free state, all alkali metals exhibit ON zero but exhibit ON of `.+1` in their compounds on account of strong tendency to lose `ns^(1) e^(-)` because of low `Delta_(i)H_(1)`. They never exhibit `.+2` and higher oxidation numbers in their compounds as the loss of 2nd electron is quite difficult on account of every high `Delta_(i)H_(2)`. |
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| 173. |
Carnallite on electrolysis givesA. Ca and `Cl_(2)`B. Na and `CO_(2)`C. Al and `Cl_(2)`D. Mg and `Cl_(2)` |
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Answer» Correct Answer - D Carnallite is `(KCl. MgCl_(2).6H_(2)O`. Since the reduction potential of `Mg^(2+)` is higher than that of `K^(+)`, the following reactions take place during electrolysis. At anode `2Cl^(-)-2e^(-)rarrCl_(2)` At cathode `(Mg^(2+)2e^(-)rarrMg)` |
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| 174. |
Which of the following is almost insoluble in water?A. LilB. KlC. RbID. CsI |
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Answer» Correct Answer - D The low solubility of Csl is due to the smaller hydration enthalpy of its two ions. |
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| 175. |
Which of the following dissovles in water to produce hydroxides?A. NaB. `Na_(2)O`C. `Na_(2)O_(2)`D. `NaO_(2)` |
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Answer» Correct Answer - D All the alkali metals, their oxides, peroxides, and superoxides readily dissolve in water to produce the corresponding hydroxides which are strong alkalies: `2Na+2H_(2)Orarr2NaOH+H_(2)` `Na_(2)Orarr2NaOH` `Na_(2)O_(2)+2H_(2)Orarr2NaOH+H_(2)O_(2)` `2NaO_(2)+2H_(2)Orarr2NaOH+H_(2)O_(2)+O_(2)` The last three reactions corresponed to the hydrolysis of oxides, peroxides, and superoxides, respectively. |
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| 176. |
Which of the following reacts with cold water quite readily ?A. CaB. SrC. BeD. All of these |
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Answer» Correct Answer - D These metal have standard reduction potentials similar to those of the corresponding group 1 metals, i.e., they are quite high in the electrochemical series. The reactivity of these metals increases as we move down the group. However, they are less reactive relative to alkali metals. |
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| 177. |
Wwhich of the following statements are true about the alkali metals?A. All alkali metals form oxo salts such as carbonates, sulphates and nitratesB. the basic character of oxides increases down the groupC. Carbonates and sulphates of lithium are stable and their stability decreases down the groupD. Solubility of carbonates and sulphates increases down the group. |
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Answer» Correct Answer - C Carbonates and sulphates of lithium decompose on heating while the stability of carbonates and sulphates of other metlas increases down the group. |
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| 178. |
Be and Al exhibit diagonal relationship. Which of the following statements about them is/are not true? (i) both react with HCl to liberate `H_(2)`. (ii) Theey are made passive by `HNO_(3)`. (iii) Their carbides give acetylene on treatment with water. (iv) Their oxides are amphoteric.A. (iii) and (iv)B. (i) and (iii)C. (i) onlyD. (iii) only |
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Answer» Correct Answer - D The carbides of both Be and Al liberate methane with water. `Be_(2)C+2H_(2)O to 2BeO+CH_(4)` `Al_(4)C_(3)+6H_(2)O to 2Al_(2)O_(3)+3CH_(4)` |
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| 179. |
Which of the following compounds is covalent?A. CaOB. `MgSO_(4)`C. `Ba(NO_(3))_(2)`D. `BeF_(2)` |
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Answer» Correct Answer - A All the compounds of Be are essentially covalent in the anhydrous state. |
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| 180. |
Which of the following chlorides does not respond to the flame test?A. `MgCl_(2)`B. `CaCl_(2)`C. `SeCl_(2)`D. `BaCl_(2)` |
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Answer» Correct Answer - A Except `BeCl_(2)` and `MgCl_(2)`, the chlorides of other alkaline earth metals impart characteristic colors to flame. |
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| 181. |
Which of the following compounds has the highest temperature of decomposition ?A. `BeSO_(4)`B. `CaSO_(4)`C. `MgSO_(4)`D. `SrSO_(4)` |
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Answer» Correct Answer - D Sulphates of alkaline earth metals are all white slids and ralatively more stable to heat that the correesponding carbonates. On heating they all decompose giving the metal oxides: `MSO_(4)overset(Delta)toMO+SO_(3)` The more basic the metal, the more stable is the sulphate thus, like carbonates, the temperature of decomposition (related to thermal stability) of sulphates of group 2 elements increases as the electropositive character of the metal or the basic strength of metal hydroxide increases down the group. |
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| 182. |
Which of the following sulphates is useful in diagnosing stomach or duodenal ulcers ?A. `BaSO_(4)`B. `SrSO_(4)`C. `CaSO_(4)`D. `MgSO_(4)` |
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Answer» Correct Answer - A `BaSO_(4)` is both insoluble in water and opaque to X rays. Thus, it is used as a barium meal to provide a shadow of the stomach or duodenum on an X-ray picture, which is useful in diagosing stomach or duodenal ulcers. The practically no solubility of `BaSO_(4)` in water is used to detect as well as estimate `SO_(4)^(2-)` ions. |
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| 183. |
Plaseter of Paris, a white powder, isA. `CaSO_(4).2H_(2)O`B. `CaSO_(4).(1)/(2)H_(2)O`C. `CaSO_(4)`D. `CaSO_(4).H_(2)O` |
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Answer» Correct Answer - B It is calcium suphate hemithydrate. |
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| 184. |
Assertion: `BeSO_(4) and MgSO_(4)` are insoluble in water. Reason: `Be^(2+) and Mg^(2+)` have low hydration enthalpies.A. If both assertion and reason are true and reason is the correct explanation of assertionB. If both assertion and reason are true but reason is not the correct explanation of assertionC. If assertion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - D The greater hydration enthalpies of `Be(2+)` and `Mg^(2+)` ions overcome the lattice enthalpy facctor and therefore, their sulphates are soluble in water. |
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| 185. |
Assertion: The melting and boiling points of the alkali metals are low. Reason: Alkali metals have weak metalli bonding.A. If both assertion and reason are true and reason is the correct explanation of assertionB. If both assertion and reason are true but reason is not the correct explanation of assertionC. If assertion is true but reason is false.D. If both assertion and reason are false. |
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Answer» Correct Answer - B Alkali metals have weak metallic bonding due to the presence of only a single valence electron in them. |
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| 186. |
Which of the following statements is/are true for all the alkali metals ?A. Their nitrates decompose on heating to give `NO_(2) and O_(2)`.B. Their corbonates decompose on heatig to give `CO_(2)` and metal oxide.C. They react with oxygen to give mainly the oxide `MO_(2)`D. They react with halogens to give halides `M^(+)X^(-)`. |
| Answer» Correct Answer - D | |
| 187. |
Name the ions present in solution of ammonia and alkali metals. |
| Answer» Ammoniated cations and ammoniated electrons. | |
| 188. |
Arrange the alkali metals in increasing order of their density.A. `Li lt Na lt K lt Rb lt Cs`B. `Cs lt Rb lt K lt Na lt Li`C. `Li lt K lt Na lt Rb lt Cs`D. `K lt Na lt Li lt Rb lt Cs` |
| Answer» Correct Answer - D | |
| 189. |
Name alkali metals in increasing order of atomic number. |
| Answer» Lithium, sodium, potassium, Rubidium, Caesium and Francium. | |
| 190. |
Write the reason behind the digonal relationship among element. |
| Answer» The diagonal relationship is due to the similarity in ionic sizes of the elements. | |
| 191. |
Diagonal Relationship Of Lithium With Magnesium |
| Answer» Correct Answer - Magnesium | |
| 192. |
Beryllium shows a diagonal relationship with |
| Answer» Correct Answer - Aluminium | |
| 193. |
Write one similarity between lithium and magnesium. |
| Answer» The oxides, `LiO_(2) and MgO` do not combine with excess oxygen to give any superoxide. | |
| 194. |
Write one similarity between Be and Al. |
| Answer» Like aluminium, beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal. | |
| 195. |
Dead burnt plaster isA. `CaSO_(4)`B. `CaSO_(4)(1)/(2)H_(2)O`C. `CaSO_(4).H_(2)O`D. `CaSO_(4).2H_(2)O` |
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Answer» Correct Answer - A Plaster of Paris is prepared by heating gypsum at `120^(@)C`. `underset("Gypsum")(2CaSO_(4).2H_(2)O)rarr underset("Plaster of Paris")((CaSO_(4))_(2).(1)/(2)H_(2)O)+3H_(2)O` On heating plaster of Paris at `200^(@)C`, if forms anhydrous calcium sulphate i.e., dead plaster which has no setting property as at absorbs water very slowly. `CaSO_(4).(1)/(2)H_(2)O overset(200^(@)C)rarr underset("Anhydride")(CaSO_(4)) overset(1100^(@)C)rarr CaO +SO_(3)` |
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| 196. |
Which of the following reacts with water liberating `NH_(3)` ?A. `Be_(3)N_(2)`B. `Mg_(3)N_(2)`C. `Ca_(3)N_(2)`D. All of these |
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Answer» Correct Answer - D `Be_(3)N_(2)` is rather volatile due to the greater tendency of Be to covalency, but other nitrodes are not volatile. All the nitrides are crystalline solids which decompose on heating and ract with water liberating `NH_(3)` `M_(3)N_(2)+6H_(2)Oto3M(OH)_(2)+2NH_(3)` |
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| 197. |
Which of the following group 2 elements does not form a nitride ?A. BeB. MgC. CaD. All group 2 elements form nitrides |
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Answer» Correct Answer - D All group 2 elements burn in `N_(2)` to form nitrides `M_(2)N_(2)` on account of high lattice enthalpy provided by high charge densities of `M^(2+) " and" N^(3-)` ions. |
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| 198. |
The reaction of which of the following groups 2 elements with oxygen is used to start a thermite reaction with A1?A. BeB. MgC. CaD. Sr |
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Answer» Correct Answer - B Mg burns with dazzling brilliance in air and evoles a lot of heat. This is used to start a thermite reaction with A1 and also to provide light in flash photography using light bulbs, not electronics. |
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| 199. |
Group 2 halides, `MX_(2)`, can be made byA. heating the metals with the halogenB. the action of halogen acid on the metalC. the action of halogen acid on the metal carbonate, metal hydroxide, and metal oxideD. all of these |
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Answer» Correct Answer - D `Ca+Cl_(2)overset(Delta)toCaCl_(2)` `Ca+2CHl toCaCl_(2)+H_(2)` `CaCO_(3)+HCl toCaCl_(2)+H_(2)O+CO_(2)` `CaO+2HCl toCaCl_(2)+H_(2)O` `Ca(OH)_(2)+2HCl toCaCl_(2)+2H_(2)O` |
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| 200. |
The solubility of most of the alkali metal halides except those of ___ decreases on descending the group.A. fluoridesB. chloridesC. bromidesD. iodides |
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Answer» Correct Answer - A Since the decrease in hydration entalpy is more than the corresponding decrease in the lattice enthalpy. In case of fluorides, the reverse takes place. |
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