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.
| 51. |
Epsom salt isA. `MgSO_(4).7H_(2)O`B. `CaSO_(4).2H_(2)O`C. `CaSO_(4)`D. `FeSO_(4).(NH_(4))_(2)SO_(4).6H_(2)O` |
| Answer» Correct Answer - A | |
| 52. |
`MgSO_(4)` on reaction with `NH_(4)OH` and `Na_(2)HPO_(4)` forms a white crystalline. What is its formulla?A. `Mg(NH_(4))PO_(4)`B. `Mg_(3)(PO_(4))_(2)`C. `MgCl_(2).MgSO_(4)`D. `MgSO_(4)` |
|
Answer» Correct Answer - A A white precipitate of magnesium ammonia phosphate is formed. `MgSO_(4)+Na_(2)HPO_(4)+NH_(4)OH rarr underset("White ppt.")(Mg(NH_(4))PO_(4)darr +Na_(2)SO_(3)+H_(2)O` |
|
| 53. |
Solubility of an ionic compound in water is mainly dependent on: a.Lattice enthalpy , b. Hydration enthalphy Both these factors oppose each other and the resultant of these determines the solubility of an ionic compound in water. If lattce enthalpy has greater value, the compound is less soluble. In case hydration enthalpy has greater value, the compound is highly soluble in water. Compound is soluble in water ifA. Hydration enthalpy is greater than lattice enthalpyB. Hydration enthalpy is less than lattice enthalpyC. hydration enthalpy and lattice enthalpy are sameD. None of the above |
|
Answer» Correct Answer - A If hydration enthalpy is greater than the lattice enthalpy, electrostatic force of attraction between the cation and the anion is easily overcome and the ionic compound dissolves in water. |
|
| 54. |
Which of the following salt will give a green colour in fire works?A. `Ca`B. `Ba`C. `Mg`D. `Sr` |
|
Answer» Correct Answer - B `Ba` imparts green colour in the Bunsen flame. |
|
| 55. |
Which of the following metal reacts with cold `H_(2)O` with the evolution of `H_(2)` gas?A. `Ca`B. `Al`C. `Zn`D. `Cu` |
|
Answer» Correct Answer - A `Ca+2H_(2)OrarrCa(OH)_(2)+H_(2)` |
|
| 56. |
Identify the correct statement`(s)`.A. Gypsum contains a lower percentage of calcium than plaster of paris.B. Gypsum is `CaSO_(4).2H_(2)O`.C. Plaster of paris is obtained by hydration of gypsum.D. Gypsum is obtained by hydration of plaster of paris. |
|
Answer» Correct Answer - A::B::D Gypsum is `CaSO_(4).2H_(2)O` and plaster of Pairs is `CaSO_(4)(1)/(2)H_(2)O`. Hence the `%` of `Ca` in gypsum is less than plaster of Paris. |
|
| 57. |
The second ionisation enthalpy of the elements of group `1` are higher than those of elements of group `2`. Explain. |
|
Answer» The second electron in case of alkali metals is to be removed from unipositive cation which has acquired highly stable noble gas configuration, e.g. `underset([Ne]3s^(1))(Na)overset(IE_(1))underset(-e^(-))rarr underset(underset(underset("gas configuration")("Stable noble"))([Ne]3s^(0)))(Na^(+)) overset(IE_(2))underset(-e^(-))rarrNa^(2+)` Whereas in case of alkaline earth metals, the seconds electron is to be removed from a cation which will acquire the stable noble gas configuration after the removal of second electron, e.g. `underset([Ne]3s^(1))(Na) overset(IE_(1))underset(-e^(-))rarr underset([Ne]3s^(1))(Mg^(o+))overset(+IE_(2))underset(-e^(-))rarr underset([Ne]3s^(0))(Mg^(2+))` That is whyc the second ionisation enthalpy of ground 1 elements is much higher than those of group 2 elements. |
|
| 58. |
What is the order of the second ionisation enthalpy of `K,Ca` and `Ba`? |
|
Answer» `KgtCagtBa` Since the second ionisation enthalpy of alkali metals is much higher as compared to alkaline earth metals. Also, down the group `(darr)`, ionisation energy decreases and hence the order. |
|
| 59. |
Give reasons for the following: (a). Alkanline earth metals cannot be obtained by chemical reduction. (b). Alkaline earth metals have stronger tendancy to form complexes than alkai metals. (c ). Magnesium nitride on reacting with water gives ammonia, but magnesium chloride does not give `HCI` on reacting with water. |
|
Answer» a. Alkaline earth metals cannot be obtained by chemical reduction, as they themselves are stronger reducing agents than common reducing agents. With carbon,they form carbides. b. As compared to alkali metals, alkaline earth metal cation have i. Smaller size, ii. Greater charge Hence, charge to radius ration or positive field of alkaline earth metals is greater, hence thery have greater tendency to form complexes. c. Magnesium nitride, `Mg_(3)N_(2)`, is a salt of `Mg(OH)_(2)`, a strong base and `NH_(3)`, a weak acid, gets hydrolysed to give `NH_(3)`. `Mg_(3)N_(2)+6H_(2)Orarr3Mg(OH)_(2)+2NH_(3)` Whereas magnesium chloride, `MgCl_(2)`, is a salt of `Mg(OH)_(2)`, a strong base and `HCI`, a strong acid, hence it does not get hydrolysed. |
|
| 60. |
Give reasons for the following:A. `BeO` is used as a refractory material.B. Beryllium halides are polymeric.C. `Be(OH)_(2)` dissolves in `NaOH`, but `Ca(OH)_(2)` does notD. On hydrolysis at room temperature, `Mg_(3)N_(2)` gives ammonia, whereas `MgCl_(2)` gives `HCl`. |
|
Answer» `BeO` has high lattice enthalpy due to smaller ionic size and greater charge on `Be^(2+)` and `O^(2-)` ions. Hence, `beO` has high melting point and is used as a refractory material. (b). Beryllium halides are electron-deficient compounds since they only four electrons in the valence shell. to complete their octet, they undergo polymerisation. (C ). `Be(OH)_(2)` being amphoteric dissolves in `NaOH` forming sodium beryllate. `Be(OH)_(2)+2NaOHrarrNa_(2)BeO_(2)+2H_(2)O` Whereas `Ca(OH)_(2)` being basic, does not dissolve in `NaOH`. (d). `Mg_(3)N_(2)` is a salt of strong base `[Mg(OH)_(2)]` and a weak acid `(NH_(3))` and hence on hydrolysis gives `NH_(3)`. `Mg_(3)N_(2)+6H_(2)Orarr3Mg(OH)_(2)+2NH_(3)` `MgCl_(2)` is a salt of strong base, `Mg(OH)_(2)`, and strong acid, `HCl`, and hence does not hydrolyse. |
|
| 61. |
What happens when:A. magnesium is burnt in airB. Quicklime is heated with silicaC. Chlorine reacts with slaked limeD. Calcium nitrate is heated |
|
Answer» (i). When magnesium is burnt in air, it gives brilliant flame forming magnesium oxide and magnesium nitride. `2Mg+O_(2)rarr2MgO` (Magnesium oxide) `3Mg+N_(2)rarrMg_(3)N_(2)` (Magnesium nitride) (ii). When quicklime `(CaO)` is heated with silica, it forms calcium silicate. `CaO+SiO_(2)overset(Above 1270 K)(rarr) underset(("Calcium sillicate"))(CaSiO_(3))` (iii). When chlorine reacts with slaked lime, it forms bleaching powder. `underset(("Slaked lime"))(Ca(OH)_(2))+Cl_(2)rarrunderset(("Bleaching powder"))(CaOCl_(2)+H_(2)O)` (iv). When calcium nitrate is heated, it decomposed to give `CaO,NO_(2)` and `O_(2)`. `2Ca(NO_(3))_(2)overset(rarr)2CaCO+4NO_(2)+O_(2)uarr` |
|
| 62. |
Chemical `(X)` is used for water softening to remove temporary hardness. `(X)` reacts with sodium carbonate to generate caustic soda. When `CO_(2)` is bubbled through `(X)`? |
|
Answer» `Ca(OH)_(2)` is used for water softening to remove temporary hardness. `underset((X))(Ca(OH)_(2))+CaHCO_(3)rarr2CaCO_(3)darr+2H_(2)O` `Ca(OH)_(2)+Na_(2)CO_(3)rarrunderset("or caustic soda")underset("Sodium hydroxide")(2NaOH+caCO_(3))` `Ca(OH)_(2)+CO_(2)rarrunderset("Milkiness")(CaCO_(3)darr+H_(2)O` Hence, `(XX)` is `Ca(OH)_(2)`. |
|
| 63. |
Describe two important uses of each of the following a. Caustic soda b. Sodium carbonate c. Quicklime |
|
Answer» Important uses of (i). Caustic soda: (a). Used in the manufacture of soap, paper, artificial silk and a number of chemicals. (b). Used in petroleum refining and purification of bauxite. (ii). Sodium carbonate: (a). Used for the manufacture of soap, glass, paper, borax, caustic soda etc. (b). Used in textile industry and also in petroleum refining. (iii) Quiclime: (a). Used in the manufacturing of dye stuffs. (b). Used in the manufacture of sodium carbonate from caustic soda. |
|
| 64. |
Compare and contrast the chemistry of group `1` metals with that of group `2` metals with respect toA. Nature of oxidesB. Solubility and thermal stability of carbonatesC. Polarising power of cationsD. Reactivity and reducting power |
|
Answer» (a) .Nature of oxides: Alkali metals 1. They form oxide, peroxide and superoxide, i.e. `M_(2)O,M_(2)O_(3)` and `MO_(2)` respectively. 2. Readily soluble in water to form hydroxide. They are crystalline solids. Alkaline earth metals 1.They react slowly and form oxides and peroxides, i.e. `MO` and `MO_(2)` respectively. 2. Less soluble in water and form hydroxide. Yheir insolubility is due to their large lattice enthalpy. (b). Solubility and thermal stability of carbonates: Alkali metals 1. The carbonates of alkali metals are highly soluble in water. 2. The carbonates of alkali metals are highly metals are highly stable to heat. Alkaline earth metals 1. The carbonates of alkaline earth metals are sparingly soluble in water. 2. They decompose on heating and the stability increases down the group. (c ). Polarising power of cations: Alkali metals The alkali metal ions have the lowest polarising power. it is because their charge//radius ratio is very low. `Li^(o+)` has the highest polarising power among its group. Alkaline earth metals teh alkaline earth metal ions have high polarising power because they form bivalent ions and their charge/radius ration is higher than the alkali meats. (d). Reactivity and reducing power: Alkali metals 1. Alkali metals are highly reactive due to their low ionisation enthalpy and low heat of formation which decreases down the group `(darr)`. 2. The alkali metals are highly electropositive and are strong reducing agents. The `E^(Θ)` values are very high of alkali metals. Alkaline earth metals 1. Because of their low ionisation enthalpy and high electropositive character, these metals are also very reactive but less reactive than alkali metals. 2. These metals are also strong reducing agents but less than alkali metals. They have least negative value and high enthalpy of formation. |
|
| 65. |
Lattice enthalpies of `BeF_(2),MgF_(2),CaF_(2) and BaF_(2)` are `-2906,-2610,-2459 and -2367 kJ mol^(-1)` resoectively. Hydration enthalpies of `Be^(2+),Ca^(2+),Ba^(2+) and F^(Θ)` are `-2194,-1921,-1577,-130 and -457 kJ mol^(-1)` respectively. Which of the fluorides has the highest solublility in water? |
|
Answer» For `BeF_(2)`, `Delta_(hyd)H^(Θ)(BeF_(2))=Delta_(hyd)H^(Θ)(Be^(2+))+2Delta_(hyd)G^(Θ)(F^(Θ))` `=[-2494+2(-457)]kJ mol^(-1)` `=-3408 kJ mol^(-1)` `Delta_(U)H^(Θ)(BeF_(2))=-2906 kJ mol^(-1)` `Delta_("Soln")H^(Θ)(BeF_(2))=Delta_(hyd)H^(Θ)(BeF_(2))-Delta_(U)H^(Θ)(BeF_(2))` `=[-3408-(-2906)]kJ mol^(-1)` `=-502 kJ mol^(-1)` For `MgF_(2)`, `Delta_(hyd)H^(Θ)(MgF_(2))=Delta_(hyd)H^(Θ)(Mg^(2+))+2Delta_(hyd)H^(Θ)(F^(Θ))` `=[-1921+2(-457)]kJ mol^(-1)` `=-2835 kJ mol^(-1)` `Delta_(U)H^(Θ)(MgF_(2))=-2610 kJ Mol^(-1)` `Delta_("soln")H^(Θ)(MgF_(2))=Delta_(hyd)H^(Θ)(MgF_(2))-Delta_(U)H^(Θ)(MgF_(2))` `=[-2835-(-2610)]kJ mol^(-1)=-225 kJ mol^(-1)` For `CaF_(2)`, `Delta_(hyd)H^(Θ)(CaF_(2))=Delta_(hyd)H^(Θ)(Ca^(2+))+2Delta_(hyd)H^(Θ)(F^(Θ))` `=[-1577+2(-457)] kJ mol^(-1)` `=-2491 kJ mol^(-1)` `Delta_(U)H^(Θ)(CaF_(2))=-2459 kJ mol^(-1)` `Delta_("soln")H^(Θ)(CaF_(2))=Delta_(hyd)H^(Θ) (CaF_(2))-Delta_(U)H^(Θ)(CaF_(2))` `=[-2491-(-2459)] kJ mol^(-1)` `=-32 kJ mol^(-1)` For `BaF_(2)`, `Delta_(hyd)H^(Θ)(BaF_(2)=Delta_(hyd)H^(Θ)(Ba^(2+))+2Delta_(hyd)H^(Θ)(F^(Θ))` `=-1305+2(-457)` `=-2219 kJ mol^(-1)` `Delta_(U)H^(Θ)(BaF_(2))=-2367 kJ mol^(-1)` `Delta_("soln")H^(Θ)(BaF_(2))=Delta_(hyd)H^(Θ)(BaF_(2))-Delta_(U)H^(Θ)(BaF_(2))` `=[-2219-(-2367)] kJ mol^(-1)` `=148 kJ mol^(-1)` Since enthalpy of solution `Delta_("soln")H^(Θ)` is maximum for `BeF_(2)`, it has highest solubility in water. |
|
| 66. |
The ionisation enthalpy of alkaline earth metals isA. Greater than alkali metals but less than elements of group `13`B. less than alkali metalsC. Greater than elements of groups `1` and `13`D. Equal to alkali metals |
|
Answer» Correct Answer - C Due to high effective charge |
|
| 67. |
Salt used as a purgative isA. `NaCl`B. `MgCl_(2).6H_(2)O`C. `MgSO_(4).7H_(2)O`D. `Ca_(3)Al_(2)6` |
| Answer» Correct Answer - C | |
| 68. |
The metal that is extracted from sea water isA. `Mg`B. `Ca`C. `Be`D. `Ba` |
| Answer» Correct Answer - A | |
| 69. |
`BeH_(2)` contains three centre two electron bond. |
| Answer» Correct Answer - T | |
| 70. |
Assertion (A): Beryllium compounds are covalent in nature. Reason (R ): The size of `Be^(2+)`ion is larger in compariso to the radii of the other divalent ions of alkaline earth metals.A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`.B. If both `(A)` and `(R )` are correct, but `(R )` is not the correct explanation of `(A)`.C. If `(A)` is correct, but `(R )` is incorrect.D. If `(A)` is incrrect, but `(R )` is correct. |
|
Answer» Correct Answer - C Correct reason: Due to small size and high charge on `Be^(2+)` polarising power of `Be^(2+)` is high and it forms convalent compounds. |
|
| 71. |
`CaH_(2)` and `BaH_(2)` are covalent in nature. |
|
Answer» Correct Answer - F `CaH_(2)` and `BaH_(2)` are ionic in nature. |
|
| 72. |
The following compounds have been arranged in order of their increasing stabilities. Identify the correct order. `K_(2)CO_(3)(I),MgCO_(3)(II),CaCO_(3)(III),BeCO_(3)(IV)`A. `I lt II lt III lt IV`B. `IV lt II lt III lt I`C. `IV lt II lt I lt III`D. `II lt IV lt III lt I` |
|
Answer» Correct Answer - B `BeCO_(3) lt MgCO_(3) lt CaCO_(3) lt K_(2)CO_(3)` Alkali metal carbonates are stable than carbonates of alkaline earth meatals, and they do not decompose on heating and their stabilities increase down the group `(darr)`, therefore potassium carbonate is thermally most stable. `MgCO_(3)overset(Delta)(rarr)MgO+CO_(2)` |
|
| 73. |
Silica reacts with magnesium to form magnesium compound `(X).(X)` reacts with dilute `HCI` and forms `(Y)`.A. `Mgo`B. `MgSiO_(3)`C. `SiCl_(4)`D. `MgCl_(2)` |
|
Answer» Correct Answer - D `SiO_(2)+Mgrarrunderset((X))(MgSiO_(3))overset(HCl)(rarr)underset((Y))(MgCl_(2))` |
|
| 74. |
Magnesium wire burns in the atomosphere of `CO_(2)` becauseA. Magnesium acts as an oxidising agentB. magnesium has two electrons in the outermost orbitalC. Magnesium acts as a reducing agent and removes oxygen from `CO_(2)`D. None of the above |
|
Answer» Correct Answer - C `2Mg+CO_(2)rarr2MgO+C` |
|
| 75. |
Which of the following is used as an antacid?A. `MgO`B. `Mg(OH)_(2)`C. `MgSO_(4)`D. `MgCO_(3)` |
|
Answer» Correct Answer - B Due to strong basic character of `Mg (OH)_(2)`. |
|
| 76. |
`Mg` burns in air to giveA. `Mg_(3)N_(2)`B. `MgO`C. `MgO and Mg_(3)N_(2)`D. `MgO and Mg_(3)N_(2)` |
|
Answer» Correct Answer - C `Mg` reacts both with `O_(2)` and `N_(2)` present in air to form `MgO` and `Mg_(3)N_(2)`. `2Mg+O_(2)rarr2MgO` `3Mg+N_(2)rarrMg_(3)N_(2)` |
|
| 77. |
The enthlpy of formation of hypothetical `CaCl_((s))` theoretically found to be `-188 kJ mol^(-1` and the `Delta_(f)H^(Θ)` for `CaCl_(2(s))` is `-795 kJ mol^(-1)`. Calculate the `Delta_(f)H^(Θ)` for the disproportionation reaction. `2 CaCl_((s))rarrCaCl_(2(s))+Ca_((s))` |
|
Answer» Given, `Delta_(f)H^(Θ) "for" CaCl=-188 kJ mol^(-1)` `Delta_(f)H^(Θ) "for" CaCl=-795 kJ mol^(-1)` `Ca_((s))+(1)/(2)Cl_(2(s)) rarr CaCI_((s)) Delta_(f)H_(1)^(Θ)=-188 kJ mol^(-1)`…(i) `Ca_((s))+Cl_(2(g))rarrCaCl_(2(s))Delta_(f)H_(2)^(Θ)=-795 kJ mol^(-1)`…(ii) To calculate `Delta_(f)H_(3)^(Θ)` for disproportionation reaction: `2CaCl_((s))rarrCa_((s))+CaCl_(2(s)), Delta_(f)H_(3)^(Θ)=?`...(iii) `Delta_(f)H_(3)^(Θ)=Delta_(f)H_(2)^(Θ)-2Delta_(f)H_(1)^(Θ)` `=-795-(2xx-188)=-419 kJ mol^(-1)` Hence, `Delta_(f)H^(Θ)` for disproportionation of `CaCl_((s))` is `-419 kJ mol^(-1)`. |
|
| 78. |
Which of the following gives propyne on hydrolysis?A. `Al_(4)C_(3)`B. `Mg_(2)C_(3)`C. `B_(4)C_(3)`D. `La_(4)C_(3)` |
|
Answer» Correct Answer - B `Mg_(2)C_(3)+4H_(2)Orarr2Mg(OH)_(2)` `+HC-=C-CH_(3)` |
|
| 79. |
Which of the following is used for taking the `X-`ray spectra of the digestive system:A. `CaSO_(4)`B. `BaSO_(4)`C. `MgSO_(4)`D. `BaCO_(3)` |
|
Answer» Correct Answer - B Barium meal, `BaSO_(4)`, as it is insoluble. |
|
| 80. |
Among the given statements, the incorrect one isA. Be differs much from other alkali metals than `Li` does from other alkali metals.B. Be generally forms covalent compounds.C. Be forms a very strong complex, `[Be(H_(2)O)_(4)]^(2+)`.D. Be usually has more than four water of crystallisation associated with it. |
|
Answer» Correct Answer - D Hydrated `Be^(2+)` ion exists as `[Be(H_(2)O)_(4)]^(2+)`. |
|
| 81. |
Both alkali metals and alkaline earth metals are `s-`block elements. They resemble each other in many respects but still there are certain dissimilarities in their properties due to different number of electrons in the valence shell, different atomic radii, ionisation enthalpy, electronegativity, etc. Like lithium, Be also differs from rest of the alkaline earth metals on account of its small atomic size and high electronetativity. `Be^(2+)`ion is very small and exerts a high polarising effect on any anion associated with it. The alkaline earth metal which does no directly combine with hydrogen isA. `Be`B. `Ca`C. `Sr`D. `Ba` |
|
Answer» Correct Answer - A Be reacts with `O_(2)`(air) which resuclts in the formaton of thin layer of `BeO` over `Be`. Hence, Be does not directly conbine with `H_(2)`. |
|
| 82. |
Both alkali metals and alkaline earth metals are `s-`block elements. They resemble each other in many respects but still there are certain dissimilarities in their properties due to different number of electrons in the valence shell, different atomic radii, ionisation enthalpy, electronegativity, etc. Like lithium, Be also differs from rest of the alkaline earth metals on account of its small atomic size and high electronetativity. `Be^(2+)`ion is very small and exerts a high polarising effect on any anion associated with it. The solubility in water of sulphates down the group `(darr)` is `BegtMggtCagtSrgtBa`. this si due toA. Increases in melting pointB. Increases in molecular massC. Decreases in lattice enthalpyD. High heat of solvation for smaller ions |
|
Answer» Correct Answer - D . for smaller ions,there is high heat of solvation |
|
| 83. |
Both alkali metals and alkaline earth metals are `s-`block elements. They resemble each other in many respects but still there are certain dissimilarities in their properties due to different number of electrons in the valence shell, different atomic radii, ionisation enthalpy, electronegativity, etc. Like lithium, Be also differs from rest of the alkaline earth metals on account of its small atomic size and high electronetativity. `Be^(2+)`ion is very small and exerts a high polarising effect on any anion associated with it. Which is least thermally stable?A. `Li_(2)CO_(3)`B. `MgCO_(3)`C. `BaCO_(3)`D. `BeCO_(3)` |
|
Answer» Correct Answer - B `MgCO_(3)` has maximum incompatibility in size of `Mg^(2+)` and `CO_(3)^(2-)` and hence maximum thermally unstable. `MgCO_(3)rarrMgO+CO_(2)` |
|
| 84. |
Both alkali metals and alkaline earth metals are `s-`block elements. They resemble each other in many respects but still there are certain dissimilarities in their properties due to different number of electrons in the valence shell, different atomic radii, ionisation enthalpy, electronegativity, etc. Like lithium, Be also differs from rest of the alkaline earth metals on account of its small atomic size and high electronetativity. `Be^(2+)`ion is very small and exerts a high polarising effect on any anion associated with it. Which of the following statements are true for group `2` elements?A. Lattice enthalpy of oxides, carbonates, fluorides decreases form `Be` to `Ba`.B. All form nitrides in air.C. The solubility of the hydroxides increases from `Be` toe `Ba`.D. All are correct. |
|
Answer» Correct Answer - D all options given are correct. |
|
| 85. |
Both alkali metals and alkaline earth metals are `s-`block elements. They resemble each other in many respects but still there are certain dissimilarities in their properties due to different number of electrons in the valence shell, different atomic radii, ionisation enthalpy, electronegativity, etc. Like lithium, Be also differs from rest of the alkaline earth metals on account of its small atomic size and high electronetativity. `Be^(2+)`ion is very small and exerts a high polarising effect on any anion associated with it. Which of the bicarbonate does not exist in solid state?A. `NaHCO_(3)`B. `KHCO_(3)`C. `Ca(HCO_(3))_(2)`D. `RbHCO_(3)` |
|
Answer» Correct Answer - C Alkaline earth metal bicarbinates are soluble in water. |
|
| 86. |
Alkali and alkaline earth metals have low ionisation enthalpies and hence exhibit characteristic flame colouration. They have high negative electrode potentials and hence are strong reducing agents. They dissolve in liquid ammonia to give a solution which conducts electricity and act as strong reducing agent. being stronger reducing agent than hydrogen, they are usually prepared by the electrolysis of their fused chlorides. Their oxides are basic and the basic strength increases down the group. The solubility of carbonates and sulphates of alkali and alkaline earth metals show opposite trends. only the carbonates of `Li` and alkaline earth metals decompose on heating. The bicarbonates of both alkali and alkaline earth metals on heating give carbonates. Property of alkaline earth metals that increases with their atomic number isA. Ionisation enthalpyB. Solubility of their hydroxidesC. Solubility of their sulphatesD. Electronegativity |
|
Answer» Correct Answer - B solubility of hydroxide increase down the group. |
|
| 87. |
Alkali and alkaline earth metals have low ionisation enthalpies and hence exhibit characteristic flame colouration. They have high negative electrode potentials and hence are strong reducing agents. They dissolve in liquid ammonia to give a solution which conducts electricity and act as strong reducing agent. being stronger reducing agent than hydrogen, they are usually prepared by the electrolysis of their fused chlorides. Their oxides are basic and the basic strength increases down the group. The solubility of carbonates and sulphates of alkali and alkaline earth metals show opposite trends. only the carbonates of `Li` and alkaline earth metals decompose on heating. The bicarbonates of both alkali and alkaline earth metals on heating give carbonates. The correct decreasing order of basic character of the oxides isA. `K_(2)OgtMgOgtSrOgtCs_(2)O`B. `Cs_(2)OgtK_(2)OgtSrOgtMgO`C. `MgOgtSrOgtK_(2)OgtCs_(2)O`D. `Cs_(2)OgtK_(2)OgtMgOgtSrO` |
|
Answer» Correct Answer - B Alkali metal oxides are more basic as compound to alkaline earth metal oxides. Among alkali metals and alkaline earth metals basicity increases down the group `(darr)`. Thus `Cs_(2)O` is more basic than `K_(2)O` and `SrO` is more basic than `MgO`. |
|
| 88. |
Which of the following properties show a reverse trend in moving down the group of alkali and alkaline earth metals?A. Solubility of hydroxidesB. Solubility of carbonatesC. Solubility of sulphatesD. Solubility of oxides |
| Answer» Correct Answer - B::C | |
| 89. |
Alkali and alkaline earth metals have low ionisation enthalpies and hence exhibit characteristic flame colouration. They have high negative electrode potentials and hence are strong reducing agents. They dissolve in liquid ammonia to give a solution which conducts electricity and act as strong reducing agent. being stronger reducing agent than hydrogen, they are usually prepared by the electrolysis of their fused chlorides. Their oxides are basic and the basic strength increases down the group. The solubility of carbonates and sulphates of alkali and alkaline earth metals show opposite trends. only the carbonates of `Li` and alkaline earth metals decompose on heating. The bicarbonates of both alkali and alkaline earth metals on heating give carbonates. Which of the following process is used in the extractive metallurgy of sodium?A. Electrolysis of aqueous solutionB. Thermite redictionC. Electrolysis of fused saltD. Self-reduction |
| Answer» Correct Answer - C | |
| 90. |
Alkaline earth metals are _______ reducing agents than alkali metals. |
| Answer» Correct Answer - Weaker | |
| 91. |
Second ionisation energies of alkaline earth metals are ________ than that of corresponding alkali metals. |
| Answer» Correct Answer - Less | |
| 92. |
Assertion (A): Alkaline earth metals are harder than alkali meatals. Reason (R ): Atomic radii of alkaline earth metas are smaller thant the corresponding alkali metals in the same period.A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`.B. If both `(A)` and `(R )` are correct, but `(R )` is not the correct explanation of `(A)`.C. If `(A)` is correct, but `(R )` is incorrect.D. If `(A)` is incrrect, but `(R )` is correct. |
|
Answer» Correct Answer - C Correct reason: Metallic bonding is stronger in alkaline earth metals as compared to alkali metals. |
|
| 93. |
(a) Why alkaline earth metals are harder, have higer melting ponts and higher densities than the alkali metals? (b). Why the atoms of alkaline earth metals are smaller than the corresponding alkali metals? (c ). Why alkaline earth metals have high electrical and thermal conductivities? (d). What is black ash? (e). Why the variation in physical properties of alkaline earth elements is not as regular as in the case of alkali metals? |
|
Answer» a. Alkaline earth metals have smaller size and stringer metallic bonding as compared to alkai metals, which results in closer packing in the metalic lattice. Consequently, alkaline earth metals are harder, have higher melting points and densities as compared to alkali metals. b. Alkaline earth metals have smaller size and stronger metallic bonding as compared to alkali metals, lattice. consequently, alkaline earth metals are harder, have higher melting points and densities as compared to alkali metals. c. Due to the presence of two loosely bound electrons in the valence electrons in the valance shell, which can freely move throughout the crystal lattice, alkaline earth metals have high thermal and electrical conductivities. d. Black ash is a mixture of `Na_(2)CO_(3)` and `CaS`. e. Since alkaline earth metals do not have the same crystal lattice structure, the variation in physical properties of alkaline earth elements is not as regular as in case of alkali metals. |
|
| 94. |
The hydration enthalpy of `Mg^(2+)` is greater thanA. `Al^(3+)`B. `Na^(o+)`C. `Ca^(2+)`D. `Sr^(2+)` |
|
Answer» Correct Answer - B Due to higher cahrge/radius ratiohn of `Mg^(2+)` as compared to `Na^(o+)`, hydration enthalpy of `Mg^(2+)` is greater than `Na^(o+)`. |
|
| 95. |
The hydration entahphy of `Mg^(2+)` ion is higer than that ofA. `Al^(3+)`B. `Be^(2+)`C. `Na^(o+)`D. `K^(o+)` |
|
Answer» Correct Answer - C::D `Mg^(2+)`ion has greater charge/radius ratio as compared to `Na^(o+)` and `K^(o+)` and hence has higher hydration enthalpy. |
|
| 96. |
Which of the following does not contain the true peroxide ion?A. `Na_(2)O_(2)`B. `H_(2)O_(2)`C. `BaO_(2)`D. `SrO_(2)` |
| Answer» Correct Answer - B | |
| 97. |
The oxidation states of the most electronegative elements in the products of the reaction between `BaO_(2)` and `H_(2)SO_(4)` areA. `0 and -1`B. `-1 and -2`C. `-2 and 0`D. `-2 and +1` |
|
Answer» Correct Answer - B `BaO_(2)+H_(2)SO_(4)rarrBaSO_(4)+H_(2)O_(2)` In `BaSO_(4)`, oxidation state of `O^(2-)` is `-2`. In `H_(2)O_(2)`, oxidation state of oxygen is `-1`. |
|
| 98. |
`BaO_(2)` is a peroxide, but `PbO_(2)` is not a peroxide. Why? |
| Answer» Metallic oxides which on treatment with dilute acids produce hydrogen peroxide are called peroxides.All peroxides contain a peroxide ion `(O_(2)^(2-))` having the structure `[O-O]^(2).PbO_(2)` does not contain peroxide ion and hence it cannot be called a peroxide. | |
| 99. |
Which is the weakest base among `NaOH,Ca(OH)_(2),KOH` and `Be(OH)_(2)`. |
| Answer» `Be(OH)_(2)`is the weakest base, since alkali metal hydroxides are stronger base than alkaline earth metal hydroxides. Also, basic character of hydroxides increases on moving down the group. Hence, `Be(OH)_(2)` is the weakest base. | |
| 100. |
Serveral blocks of magnesium are fixed to the bottom of a ship toA. Prevent aciton of water and saltB. Prevent puncturing by under sea rocksC. keep away the sharksD. Make the ship lighter |
|
Answer» Correct Answer - A To prevent corrosion. |
|