Tiêu đề 10. THE S-BLOCK ELEMENTS - 02.pdf ✅

1 ADVANCED BATCH S-Block Single Correct Question 1. One mole of a substance (X) was treated with an excess of water. Two moles of readily combustile gas was produced along with a solution which treated with CO2 produced a white turbidity. The substance (X) could be (1) Ca (2) CaH2 (3) Ca(OH)2 (4) Ca(NO3)2 2. Sodium carbonate can be manufactured by Solvay’s process but potassium carbonate cannot be prepared because: (1) K2CO3 is more soluble (2) K2CO3 is less soluble (3) KHCO3 is more soluble than NaHCO3 (4) KHCO3 is less soluble than NaHCO3 3. Compounds of alkaline earth metals are less soluble in water than the corresponding alkali metal salts due to: (1) their high ionization energy (2) their low electronegativity (3) their low hydration energy (4) their high lattice energy 4. A compound (X) on heating gives a colourless gas. The residue is dissolved in water to obtain (Y). Excess CO2 is bubbled through aqueous solution of (Y) and formation of (Z) is observed. (Z) on gently heating gives back (X). The compound (X) is (1) CaCO3 (2) Na2CO3 (3) Ca(HCO3)2 (4) K2CO3 5. On dissolving moderate amount of sodium metal in liquid NH3 at low temperature, which one of the following does not occur? (1) Blue coloured solution is obtained (2) Na+ ions are formed in the solution (3) Liquid NH3 becomes good conductor of electricity (4) Liquid NH3 remains diamagnetic. Multiple correct answer 6. Which of the following statement is correct? (1) The solubility of group 2 salt depends upon the lattice energy of the solid and hydration energy of the ions (2) The solubilities of the most of the group II salts decrease with increase in atomic weight of the corresponding metal (3) The solubilities of group 2 sulphates and hydroxide has opposite trends (4) The solubilities of group 2 fluoride and hydroxides increase with molecular weight 7. Exceptionally small size of Lithium results in : (1) Anomalous behavior of Li+ (2) Its high polarizing power. (3) It has high degree of hydration. (4) Exceptionally low ionization enthalpy 8. Which of the following statements is/are correct for compounds of group 2 metals? (1) The number of molecules of water of crystallization increases with the size of the metal ions (2) The number of molecules of water of crystallization increases with the size of the metal ions decreases (3) The number of molecules of water of crystallization decreases as the size of the metal ion increases (4) Mg & Be do not give any characteristic colour to Bunsen flame 9. Which of the following statement in incorrect? (1) The atomic radius of Na is greater than that of Mg. (2) Metallic bond in Mg is stronger than the metallic bond in Na. (3) Melting and boiling points of K are greater than those of Na. (4) Mg and Ca both impact characteristic colour to the flame. 10. the pair(s) of reagents that yield paramagnetic species is/are (1) Na and excess of NH3 (2) K and excess of O2 (3) Cu and dilute HNO3 (4) O2 and 2-ethylanthraquinol DPP -02
2 Integer Type Question 11. How many of the following are correctly matched? Element Colour in flame test K violet/Lilac Na Yellow Be Crimson red Ca Brick red Sr Apple grenn Mg No colour Rb Red violet Cs Blue Li Crimson red 12. The by product of solvay process reacts with Na2CO3 to form a compound x, which on heating decomposes to give y. y is absorbed by KO2. The number of atoms per molecule of y is ...... 13. How many of the following statement is/are correct? (a) Solvay process is used for manufacturing sodium carbonate (b) CaCl2 is obtained as by product in Solvay process. (c) NH3 can be recovered in above process. (d) MgSO4.7H2O is Epsom salt. (e) On hydrolysis of Na2CO3, we get an acidic solution due to the formation of H2CO3. (f) K2CO3 can also be prepared by Solvay process. (g) CaCO3 can be obtained by passing excess of CO2 through lime water. 14. Molecular formula of Glauber’s salt is Na2SO4.xH2O. The value of x is____. (1) heating formic acid with cone. H2SO4 (2) heating potassium ferrocyanide with cone H2SO4 (3) heating malonic acid with P4O10 (4) hydrolysis of Mg2C3 15. 2 4 3 4 3 4 4 3 2 2 A B H O (NH )HCO NH HCO NaCl C NH Cl NH Cl D 2NH 2H O CaCl + + → + → + + → + + Sum of the atoms present in one molecule each of A, B, C and D. Comprehension 01 16. A and B are (1) BeO & Be3N2 (2) BeO & BeO2 (3) BeO + Be(OH)2 (4) Be3N2 & Be(OH)2 17. C and D are (1) NH4OH (2) NH4Cl (3) NH3 & HNO3 (4) Be(OH)2 + BeO2 18. ‘E’ is (1) NH4OH (2) NH4Cl (3) NH4OH & NH4Cl (4) BeCl2 Comprehension 02 All alkali metals dissolve in anhydrous liquid ammonia to give blue colour solution. It is the ammoniated electron which is responsible for the blue colour of the solution, and the electrical conductivity is mainly due to ammoniated electron, [e(NH3)y]. Dilute solutions are paramagnetic due to free ammoniated electrons; this paramagnetism decreases at higher concentration. Above 3M concentration, the solutions are diamagnetic and no longer blue but are bronze/copper-bronze coloured with a metallic luster. 19. Which of the following statement about solution of alkali metals in liquid ammonia is correct? (1) The dilute solutions are bad conductor of electricity. (2) Both the dilute solutions as well as concentrated solution are equally paramagnetic in nature. (3) Charge transfer is responsible for the blue colour of the solution. (4) None of these. 20. Ammoniated solutions of alkali metals are reducing agents due to the : (1) solvated cation. (2) solvated unpaired electron. (3) the liberation of hydrogen gas (4) (1) and (2) both
3 Answer Key 1. ( 2 ) 2. ( 3 ) 3. ( 4 ) 4. ( 1 ) 5 . ( 4 ) 6 . (1,2,3 ) 7. (1,2,3 ) 8. (2,3,4 ) 9. (3,4 ) 10. (1,2,3 ) 11 . ( 7 ) 12 . ( 3 ) 13 . ( 4 ) 14 . (10 ) 15. (18 ) 16. ( 1 ) 17. ( 2 ) 18. ( 2 ) 19. ( 4 ) 20. ( 2 )