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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
The most aboundant ore of sodium is ____________ . |
| Answer» Correct Answer - Rock salt | |
| 52. |
Sodium reacts with excess of oxygen to form ____________ . |
| Answer» Correct Answer - `Na_(2)O_(2)` | |
| 53. |
As the size of the cation _____________ the basicity of the hydroxide increases. |
| Answer» Correct Answer - Increases | |
| 54. |
The chemical formula of chile salpetre is ___________ . |
| Answer» Correct Answer - `NaNO_(3)` | |
| 55. |
Sodium peroxide which is a yellow solid, when exposed to air becomes white due to the formation of _____________ and ___________ . |
| Answer» `NaOH` and `Na_(2)CO_(3)` | |
| 56. |
Pearl ash is ____________ . |
| Answer» Correct Answer - `K_(2)CO_(3)` | |
| 57. |
A solution of sodium sulphate in qater is electrolysed using inert electrodes, The products at the cathode and anode are respectively.A. `H_(2),O_(2)`B. `O_(2),H_(2)`C. `O_(2),Na`D. `O_(2),SO_(3)` |
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Answer» Correct Answer - A In aqueous solution: reducton potential of `H_(2)Ogt` reduction potential `Na^(o+)` . Hence, `H_(2)O` undergoes reaction at cathode to give `H_(2(g))` `H_(2)O+e^(-)rarr(1)/(2)H_(2(g))+overset(Θ)OH_((aq))` Similary, oxidation potential of `H_(2)Ogt` oxidation potential of `SO_(4)^(2-)` ions. Hence, oxidation of `H_(2)O` occurs at anode to give `O_(2(g))` `H_(2)Orarr 2H^(o+)+(1)/(2)O_(2(g))+2e^(-)` |
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| 58. |
Sodium metal cannot be stroed underA. KerosieneB. TolueneC. AlocholD. Water |
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Answer» Correct Answer - C::D Since alcohol and water both react with Na. `Na+H_(2)O rarr NaOH+(1)/(2)H_(2)` `Na+C_(2)H_(5)OH rarr C_(2)H_(5)Ona +(1)/(2)H_(2)` |
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| 59. |
How many water molecules are associated with washing soda ? |
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Answer» Correct Answer - `(10)` Washing soda is `Na_(2)CO_(3).10H_(2)O` |
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| 60. |
Potassium iodide reacts with acidified `K_(2)Cr_(2)O_(7)`. How many moles of KI are required for one mole of `K_(2)Cr_(2)O_(7)` ? |
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Answer» Correct Answer - `(6)` `[Cr_(2)O_(7)^(2-)+14H^(o+)+6e^(Θ)rarr 2Cr^(3+)+7H_(2)O]` `2I^(Θ)rarr I_(2)+2e^(Θ)]xx3` `ulbar(Cr_(2)O_(7)^(2-)+14H^(o+)+61^(Θ)rarr 2Cr^(3+)+7H_(2)O+3I_(2)` 1 mol of `K_(2)Cr_(2)O_(7)` reacts with 6 moles of KI. |
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| 61. |
How many alkali metals are known ? |
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Answer» Correct Answer - `(6)` `Li, Na, K, Rb, Cs, Fr`. |
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| 62. |
Li has the following abnormal behaviour in its group:A. Lithium carbonate decomposes into its oxide on heating, unlike other elements.B. LiCI is covalent in nature.C. `Li_(3)N` is stable compound.D. LiCI is poor conductor of electricity in molten state. |
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Answer» Correct Answer - A::B::C Due to the small size and high charge/redius ratio. |
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| 63. |
Which among the following compounds is paramagnetic ?A. `KO_(2)`B. `K_(2)O_(2)`C. `K_(2)O`D. `NO_(2)` |
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Answer» Correct Answer - A::D Due to the presence of unpaired electron on `O_(2)^(Θ)` ion in `KO_(2)` and N in `NO_(2)` |
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| 64. |
Select wrong statements about alkali metals:A. All form `(MNH)_(2)` amide.B. All form superoxides `(MO_(2))`C. All form ionic hydrides (MH)D. All form nitrides |
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Answer» Correct Answer - B::D Only K, Rb, Cs form superoxide and only Li forms nitride. |
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| 65. |
Which of the following is/are found in the solid state ?A. `LiHCO_(3)`B. `KHCO_(3)`C. `NaHCO_(3)`D. `NH_(4)HCO_(3)` |
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Answer» Correct Answer - B::C::D All are soluble in water. |
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| 66. |
When sodium is treated with sufficient oxygen/air, the product obtained isA. `NaO`B. `Na_(2)O`C. `Na_(2)O_(2)`D. `NaO_(2)` |
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Answer» Correct Answer - C `2Na+O_(2)rarr Na_(2)O_(2)` |
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| 67. |
Which of the following reaction (s) correct ?A. `CI_(2)+underset("conc soin")underset("Hot and")(NaOH)rarr NaCI+NaCIO_(3)+H_(2)O`B. `P_(4)+NaOH+H_(2)O rarr NaH_(2)PO_(2)+PH_(3)`C. `S+NaOH overset(Delta)rarr Na_(2)S_(2)O_(3)+Na_(2)S+H_(2)O`D. `C+NaOH overset(Delta)rarr Na_(2)SiO_(3)+H_(2)` |
| Answer» Correct Answer - A::B::C | |
| 68. |
Alkali metlas are characterised byA. Good conductor of heat and electricityB. High oxidation potentialsC. Low melting pointsD. Solubility in liquid ammonia |
| Answer» Correct Answer - A::B::C::D | |
| 69. |
a. when is an ion highly polarising ? Which alkali metal ion has the highest polarising power ? b. What makes lithium to show properties uncommon to the rest of the alkali metals ? |
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Answer» a. A cation highly polarising if its (charge/redius) ratio is high. `Li^(o+)` ion having the smallest size will have the maximum (charge/redius) radio or polarising power. b. Lithium show properties uncommon to the rest of alkali metals due to: i. Small size of Li atom and `Li^(o+)` ion. ii. High (charge/radius) ration of `Li^(o+)` ion. |
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| 70. |
The similarity in the properties of alkali metlas is due toA. Their same atomicityB. Similar outer shell configurationC. Same energy of outer shellD. Same energy ofouter shell |
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Answer» Correct Answer - B `ns^(1)` |
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| 71. |
Which one of the alkali metal forms only, the normal oxide, `M_(2)O` ?A. LiB. NaC. KD. Rb |
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Answer» Correct Answer - A Only Li forms `Li_(2)O` due to more lattice enthalpy of smallsized `Li^(o+)` and `O^(2-)` ions. |
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| 72. |
The peramagnetic species isA. `KO_(2)`B. `SiO_(2)`C. `TiO_(2)`D. `BaO_(2)` |
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Answer» Correct Answer - A `KO_(2)` is paramagnetic, due to the persence of unparired electron in superoxide ion, `O_(2)^(Θ)` in `KO_(2)` |
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| 73. |
Magnesium uranyl least is used forA. SodiumB. PotassiumC. RubidiumD. Caesium |
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Answer» Correct Answer - A Magnesium uranyl test for `Na^(o+)` `Na+underset(darr)(3UO_(2))(CH_(3)COO)_(2)+Mg(CH_(3)COO)_(2)` `CH_(3)COO^(Θ)+9H_(2)O+NaMg underset("acetate")underset("sodium magnesium uranyl")underset("Yellow ppt. of")((CO_(3))_(2)(CH_(3)OO)_(9)).9H_(2)O` |
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| 74. |
Give reason for the following: a. Why potassium is reactive than rubidium ? b. Irrespective of the alkali metal dissolved in liquid ammonia, dil solution is always blue coloured. |
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Answer» a. The atomicsize of potassium is smaller as compared to rubidium, thus the valence shell electron `(ns^(1))` is more loosely bound in rubidium. As a result, ionisation ethalpy of potassium is more than rubidium and hence potassium is less reactive than rubidium. b. Alkali metals dissolve in liquid ammonia to give ammoniated metal ion and ammoniated electron. `M_((s))+(x+y)NH_(3)rarr underset("metal ion")underset("Ammoniated")([M(NH_(3))_(x)])^(o+) + underset("electron")underset("Ammoniated")([e(NH_(3))_(y)])^(Θ)` The blue colour is because of ammoniated electron which absorbs energy corresponding to the red region of the visible light and gives complimentary blue colour. |
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| 75. |
Alkali metal salts ionic and soluble in water. The solubility of an ionic compound depends on (i) lattic ethalpy and (ii) hydration enthalpy. These two factor oppose each other. If hydration ethalpy is high, the ions will have greater tendency to be hydrated and therefore the solubility will be high. The smaller the cation, the greater is the degree of hydration. The reducing behaviour of alkali metals in solution is also dependent on the hydration enthalpy besides other factors. The radius of which of the hydrated ion is the highest ?A. `Li_((aq))^(o+)`B. `Na_((aq))^(o+)`C. `K_((aq))^(o+)`D. `Rb_((aq))^(o+)` |
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Answer» Correct Answer - A `Li^(o+)` ion having the smallest size and the highest charge density is the most hydrated alkali metal and thus the size of `[Li(H_(2)O)_(x)]^(o+)` or `Li^(o+)` (aq)` is highest. |
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| 76. |
Based on lattic energy and other considerations, which one of the following alkali metal chloride is expected to have the highest melting point ?A. LiCIB. NaCIC. KCID. RbCI |
| Answer» Correct Answer - B | |
| 77. |
Alkali metal salts ionic and soluble in water. The solubility of an ionic compound depends on (i) lattic ethalpy and (ii) hydration enthalpy. These two factor oppose each other. If hydration ethalpy is high, the ions will have greater tendency to be hydrated and therefore the solubility will be high. The smaller the cation, the greater is the degree of hydration. The reducing behaviour of alkali metals in solution is also dependent on the hydration enthalpy besides other factors. The hydration energy is maximum forA. `Li^(o+)`B. `Na^(o+)`C. `K^(o+)`D. `Rb^(o+)` |
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Answer» Correct Answer - A `Li^(o+)` ion having the maximum charge density is extensively hydrated ion and thus the energy released, i.e. hydration energy is also the highest. |
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| 78. |
Alkali metal salts ionic and soluble in water. The solubility of an ionic compound depends on (i) lattic ethalpy and (ii) hydration enthalpy. These two factor oppose each other. If hydration ethalpy is high, the ions will have greater tendency to be hydrated and therefore the solubility will be high. The smaller the cation, the greater is the degree of hydration. The reducing behaviour of alkali metals in solution is also dependent on the hydration enthalpy besides other factors. The ionic mobility of `Li^(o+)` is less than of the `Na^(o+)` ion in solution becauseA. `Li^(o+)` ion has a high charge density.B. `Li^(o+)` ion has the highest hydration tendency.C. `Li^(o+)` ion has the highest ionisation enthalpy.D. `Li^(o+)` ion has two electrons. |
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Answer» Correct Answer - A::B Due to its high charge density, `Li^(o+)` ion has the highest hydration tendency and thus maximum size, thus, `Li^(o+)` ion has less ionic mobility. |
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| 79. |
A binary of potassium (A) on heating with sulphar, compound (B) is formed. (B) on reacting with `BaCI_(2)` gives a white precipitate (C ) which is insoluble in concentrated HCI. Indenfity (A), (B) and (C ). |
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Answer» `(A)+S overset(Delta)rarr (B)` `(A)+BaCI_(2)rarr underset("White ppt.")(C )` (A) is binary salt of potassium. (C ) is white ppt. which is insoluble in conc HCI. `underset((A))(2KO_(2))+S overset(Delta)rarr underset((B))(K_(2)SO_(4))` `underset((B))(K_(2)SO_(4)) + BaCI rarr 2KCI+ underset("Whuite ppt.")underset((C ))(BaSO_(4)darr)` Hence, (A) is `KO_(2)` (potassium peroxide), (B) is `K_(2)SO_(4)` (potassium sulphate) and (C ) is `BaSO_(4)` (barium sulphate). |
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| 80. |
Alkali metals are paramagnetic but their salts are dimagnetic. Explain. |
| Answer» General electronic configuration of alkali metlas is `ns^(1)`. i.e. they contain one unpaired electron in their valence shell and hence are paramagnetic. However, during salt formation, this unpaired electron is transferred to the non-metallic atom forming anion. As a result a salt has paired electrons both in the cation and anion and hence alkali metal salts are dimagnetic. | |
| 81. |
Which of the following alkali metal does not form alum ?A. LiB. NaC. KD. Rb |
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Answer» Correct Answer - A `Li^(o+)` ion due to its small size does not form a stable lattice structure. |
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| 82. |
Give reason for the decreasing order of the conductivity of the following. `Cs_((aq))^(o+)gtRb_((aq))^(o+)gtK_((aq))^(o+)gtNa_((aq))^(o+)gtLi_((aq))^(o+)` |
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Answer» In aqueous medium. Ions are hydrated. `Li^(o+)` ion, because of its maximum charge to radius ratio, has maximum positive charge density and thus is heavily hydrated. On moving form `Li^(o+)` ion to `Cs^(o+)` ion, the degree of hydration decreases. As a result, the `Li^(o+)` ion is maximum hydrated and the the `Cs^(o+)` ion is least hydrated. Consequently, the size of the hydrated `Li^(o+)` ion is maximum and it has the least mobility while the size of the `Cs^(o+)` ion is minimum and it has the maximum mobility. `Cs_((aq))^(o+)gtRb_((aq))^(o+)gtK_((aq))^(o+)gtNa_((aq))^(o+)gtLi_((aq))^(o+)` |
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| 83. |
Lithium is used photoelectric cells. |
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Answer» Correct Answer - F Li does not exhibit photolectric effect as ionnisation energy of Li is much greater than the energy of photon (light), hence electron is not ejected. |
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| 84. |
Why cesium can be used in photoelectric cell, while lithium cannot be ? |
| Answer» IE of calcium is the least while that of lithium is maximum among alkali metals, thus caesium can lose electron very easily whilr lithium cannot. Thus Cs is used in photolectric cell, while Li cannot be. | |
| 85. |
Lithium water used for the treatment of gout isA. `LiHCO_(3)`B. `Li_(2)CO_(3)`C. `Li_(2)SO_(4)`D. LiOH |
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Answer» Correct Answer - A Lithium water `(LiHCO_(3))` is used for treatment of gout. `Li_(2)CO_(3)+H_(2)O+CO_(2)rarr 2LiHCO_(3)` `Li_(2)SO_(4)+(NH_(4))_(2)CO_(3)rarr Li_(2)CO_(3)+(NH_(4))_(2)SO_(4)` |
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| 86. |
Identify (A), (B), (C ) and (D) and give their chemical formulate. `(A)+NaOH overset(Delta)rarr NaCI+NH_(3)+H_(2)O` `NH_(3)+CO_(2)+H_(2)O rarr (B)` `(B)+NaCI rarr (C )+NH_(4)CI` `(C )overset(Delta)rarr Na_(2)CO_(3)+H_(2)O+(D)` |
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Answer» `underset((A))(NH_(4)CI) + NaOH overset(Delta)rarr NaCI+NH_(3)+H_(2)O` `NH_(3)+CO_(2)+H_(2)O rarr NH_(4)HCunderset((B))(O_(3))` `underset((B))(NH_(4)HCO_(3))+NaCI rarr underset((C ))(NaHCO_(3))+NH_(4)CI` `underset((C ))(2NaHCO_(3))overset(Delta)rarr Na_(3)CO_(3)+H_(2)O+underset((D))(CO_(2))` Hence, `(A) is NH_(4)CI, (B) is NH_(4)HCO_(3), (C ) is NaHCO_(3)` and (D) is CO_(2)`. |
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| 87. |
`ZnCI_(2)+NaHCO_(3)overset("Heat")rarr (A)overset("Heat")rarr (B)+(C )+H_(2)O (B)+NaOH rarr (D)` Identify the compound (D) present in the solution.A. `ZnCO_(3)`B. `Zn(OH)_(2)`C. `ZnO`D. `Na_(2)znO_(2)` |
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Answer» Correct Answer - D `ZnCI_(2)+2NaHCO_(3)overset(Delta)rarr underset((A))Zn(HCO_(3))_(2)+2NaCI` `underset((A))(Zn(HCO_(3))_(2))overset(Delta)rarr underset((B))(znCO_(3))+H_(2)O+underset((C ))(CO_(2)uarr)` `underset((B))(ZnCO_(3)+2NaOH rarr underset((D))(Na_(2)ZnO_(2))+2H_(2)O` |
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| 88. |
In the following sequence of recation, identify the compounds (A), (B), (C ) and (D): `underset("Solution")Na_(2)CO_(3)overset(SO_(2))rarr (A) overset(Na_(2)CO_(3))rarr (B) overset(S)underset("Heat")rarr (C ) overset(AgNO_(3))rarr (D)`A. `NaSO_(3).NaHSO_(3).Na_(2)s.Ag_(2)S`B. `NaHSO_(3), Na_(2)SO_(3),Na_(2)S_(2)O_(3),Ag_(2)S`C. `NaHSO_(3),Na_(2)SO_(4),Na_(2)S,Ag_(2)O`D. `Na_(2)SO_(3),Na_(2)SO_(4),Na_(2)S_(2)O_(3),Ag` |
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Answer» Correct Answer - B `Na_(2)CO_(3)+2SO_(2)+H_(2)O rarr underset((A))2NaHSO_(3)+CO_(2)` `underset((A))(2NaHSO_(3))+Na_(2)CO_(3)rarr underset((B))(2Na_(2)SO_(3))+H_(2)O+CO_(2)` `underset((B))(2Na_(2)SO_(3)+S overset("Heat")rarr underset((C ))(2Na_(2)S_(2)O_(3)` `Na_(2)S_(2)O_(3)+AgNO_(3)rarr underset((D))(Ag_(2)S)+H_(2)SO_(4)` |
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| 89. |
`NaOH+CO oversetr(200^(@)C)underset(5-10 atm)rarr A`. The product A is:A. `NaHCO_(3)`B. `Na_(2)CO_(3)`C. `HCOONa`D. `H_(2)CO_(3)` |
| Answer» Correct Answer - C | |
| 90. |
What happens when: a. Potassium metal is dropped in water b. Potassium is heated in free supply of air c. Potassium superoxide is dissolved in water |
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Answer» a. When the potassium metal is dropped in water is dropped in reacts readily with water to form potassium hydroxide and hydrogen gas is evolved. `2K_((s))+2H_(2)O rarr 2KOH_((s))+H_(2(g))uarr` b. When the potassium metal is heated in free supply of air, it burns vigorously in air form superoxide. `K_((s))+O_(2(g))rarr KO_(2(g))` c. when potassium superoxide dissolved in water, it forms `KOH, H_(2)O_(2)` and `O_(2)`. `2KO_(2)+2H_(2)O rarr 2KOH+H_(2)O rarr 2KOH+H_(2)O_(2)+O_(2)` |
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| 91. |
Alkali metals are obtained by the electrolysis of the molten salts and not by the electrolysis of their aqueous solutions. Give reason. |
| Answer» The solution of alkali metal salts contains metal ions, `H^(o+)`, `overset(Θ)OH` and the anions. The discharge potaintal of the `H^(o+)` ion is lower than the metal cations and thus, on electrolysis of solutions of alkali metal salts, hydrogen is discharged at the cathode, rather than the metal. However, on electrolysis of the molten salt, the metal cation only present gets discharged at the cathode. | |
| 92. |
The principal products obtained on heating iodine with cold and concentrated caustic soda solution:A. `NaIO+NaI`B. `NaIO+NaIO_(3)`C. `NaIO_(3)+NaI`D. `NaIO_(4)+NaI` |
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Answer» Correct Answer - A `underset(("cold and concentrated"))(2NaOH+I_(2)rarr) NaI+NaOI+H_(2)O` |
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| 93. |
which of the following has the lowest melting point ?A. LiB. NaC. KD. Cs |
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Answer» Correct Answer - D Due to the weakest metallic bonding in Cs. |
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| 94. |
The products of electrolysis of concentrated common salt solution areA. `Na+CI+(2)`B. `H_(2)+O_(2)`C. `NaOH+H_(2)+CI_(2)`D. `NaOH+CI_(2)+O_(2)` |
| Answer» Correct Answer - C | |
| 95. |
On addition of conc `HNO_(3)` to the aqeous solution of sommon salt, sodium chloride crystallises out. Give reason. |
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Answer» Aqueous sodium chloride solution cotains `NaCI(s) _ H_(2)O rarr underset(ion)underset("Hyrated sodium")([Na(H_(2)O)_(x)])^(o+) + underset(ion)underset("Hydrated chloride")([CI(H_(2)O)_(y)]^(Θ)` On addition of conc `HNO_(3)` the reaction between hydrated ions and conc `HNO_(3)` takes place, thereby water molecules which were previously forming hydrated species are removed. The ions are thus unsolvated and thus unsolvated and hence reform the crystal lattice resulting in the crystallisation of sodium chloride (NaCI). |
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| 96. |
Crude common salt is hygroscopic because of impurities of ______________ and _____________ . |
| Answer» Calcium chloride and magnesium chloride | |
| 97. |
The alkali metal having highest melting point isA. LiB. NaC. CsD. Rb |
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Answer» Correct Answer - A Due to the strongest metallic bonding. |
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| 98. |
Causticisation process is used for the preparation ofA. Caustic sodaB. Caustic potashC. Slaked limeD. Sodium carbonate |
| Answer» Correct Answer - A | |
| 99. |
The metallic lustre of sodium is explanined by the presence ofA. `Na^(o+)` ionsB. The oscillation of loosely bound electronsC. Loosely held electectronsD. bacc lattice |
| Answer» Correct Answer - B | |
| 100. |
Microcomic salt isA. `Na(NH_(4))HP_(4).4H_(2)O`B. `Na(NH_(4)).H_(2)O`C. `Na(NH_(3))HPO_(4).4H_(2)O`D. `K(NH_(4))HPO_(4).2H_(2)O` |
| Answer» Correct Answer - A | |