Title 10. THE S-BLOCK ELEMENTS.pdf ✅

(1.) Lithium, sodium, potassium, rubidium, caesium and francium are collectively known as the alkali metals, because [Page: 292] (a) they form hydroxides on reaction with water which are strongly alkaline in nature. (b) they form oxides on reaction with water which are weakly basic in nature. (c) they form hydrides on reaction with water which are acidic in nature. (d) they form oxides and hydroxides on reaction with water which are acidic in nature. (2.) Which of the following alkali metals belongs to the period number five. [Page: 292] (a) K (b) Fr (c) Rb (d) Cs (3.) Francium is highly radioactive, its longest‐lived isotope 223Fr has a half‐life of [Page: 292] (a) only 21 minutes (b) only 21 seconds (c) only 36 hours (d) only 15 minutes (4.) General electronic configuration of alkali metal is   1 Noble gas ns . Which of the following noble gas and number for ‘n’ belongs to the element Caesium? [Page: 292] (a) Noble gas = Xe, n = 4 (b) Noble gas = Xe, M = 6 (c) Noble gas = Rn, n = 5 (d) Noble gas = Rn, n = 6 (5.) Which of the following is the correct order of hydration enthalpy of alkali metal ions? [Page: 292] (a) Na Li K Rb Cs + + + + +     (b) Li Na K Rb Cs + + + + +     (c) Cs Rb K Na Li + + + + +     (d) K Na Li Rb Cs + + + + +     (6.) Which of the following statements regarding ionization enthalpy of alkali metals is correct? [Page: 292] (a) Ionization enthalpies of alkali metals are low and decreases down the group. (b) Ionization enthalpies of alkali metals are high and increases down the group. (c) Ionization enthalpies of alkali metals are low and increases down the group. (d) Ionization enthalpies of alkali metals are high and decreases down the group. (7.) Some statements are given below regarding the alkali metals/ions. [Page: 292] (I) Hydration enthalpy: Li Na K Rb Cs + + + + +     (II) Atomic radii:
Li Na K Rb Cs     (III) Ionization enthalpy: Li Na K Rb Cs     Choose the correct option. (a) Only I correct (b) I and II correct (c) I and III correct (d) I , II and III correct (8.) Among the given alkali metals, which one has the highest density. [Page: 293] (a) Li (b) Cs (c) Rb (d) K (9.) Which of the following alkali metals imparts blue colour to an oxidizing flame [Page: 292] (a) Lithium (b) Potassium (c) Rubidium (d) Caesium (10.) Which of the following alkali metals only forms monoxides and not peroxides and superoxides on reaction with oxygen ? [Page: 293] (a) Na (b) Li (c) Cs (d) K (11.) What is the toxidation state of potassium’ in potassium superoxide [Page: 293] (a) 0 (b) + l (c) + 2 (d) −1 (12.) Match the column I with column II and select the correct code given below: [Page: 292] ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Column 1 Metal Column II Colour P Li I Blue Q Na II Violet R K III Crimson red S Cs IV Yellow (a) P—I, Q—II, R—III, S—IV (b) P—III, Q—IV, R—II, S—I (c) P—II, Q—IV, R—III, S—I (d) P‐IV, Q‐III, R‐II, S‐I (13.) Which of the following statements regarding alkali metal hydride is correct [Page: 293] (a) They are ionic solid with high melting point. (b) They are covalent liquid with low melting point. (c) They are ionic liquid with low melting point.
(d) They are covalent solid with high melting point. (14.) Which of the following elements has high reducing power) [Page:294] (a) Cs (b) Li (c) Na (d) K (15.) Lithium is alloyed with which metal ro make white metal) [Page: 294] (a) Lead (b) Aluminium (c) Magnesium (d) Silicon (16.) Which alkali metal hydroxide is used in the manufacture of soft soap [Page: 294] (a) LiOH (b) NaOH (c) KOH (d) RbOH (17.) Some statements are given below, by using it choose the correct option. [Page: 294] (I) The oxides and peroxides of alkali metals are colourless when pure. (II) Caesium is used in devising photoelectric cells. (III) KOH is used as an excellent absorbent of CO . 2 (IV) Liquid sodium metal is used as a coolant in fast breeder nuclear reactors. (a) I and II are correct. (b) I, II and III are correct. (c) II, III and IV are correct. (d) I, II, III and IV are correct. (18.) The low solubility of LiF in water is due to [Page: 294] (a) its high hydration enthalpy. (b) its low hydration enthalpy. (c) its high lattice enthalpy. (d) its low lattice enthalpy. (19.) Which of the following colours gives alkali metals when it dissolves in liquid ammonia. [Page: 292] (a) Blue (b) Red (c) Orange (d) Black (20.) Choose the correct order of given physical properties of the alkali metals. [Page: 294] (a) Melting point: Li K Na Rb Cs     (b) Boiling point: Li Na K Rb Cs     (c) Density: Na Li Rb Cs K     (d) Metallic radius: K Na Li Rb Cs     (21.) Which of the following alkali metals cannot forms superoxide ( O 2 ) − ion) [Page: 293] (a) K (b) Rb
(c) Cs (d) Li (22.) Which of the following alkali metals has most negative o E value and least negative o E value Respectively? [Page: 294] (a) Li and Na (b) Na and Li (c) Li and K (d) Na and K (23.) Lithium shows less vigorous reaction with water than that of sodium. This behaviour of lithium is attributed to its [page: 294] (a) small size and very low hydration energy. (b) bigger size and very high hydration energy. (c) small size and very high hydration energy. (d) bigger size and very low hydration energy. (24.) Which among the following alkali metals has strong reducing agent ?. [Page: 294] (a) K (b) Na (c) Rb (d) Li (25.) Which of the following liquid metal is used as a coolant in fast breeder nuclear reactors [Page: 293] (a) Liquid potassium metal (b) Liquid caesium metal (c) Liquid sodium metal (d) Liquid Lithium metal (26.) Li O H 2LiO 2 2 + →O H Na O 2H O 2NaOH X 2 2 2 + → + 2 2 2KO 2H O 2KOH x y + → + + Identify x and y. [Page: 295] (a) 2 2 3 x H O , y O = = (b) 2 2 2 x O ,g H O = = (c) 2 2 2 x H O , y 0 = = (d) 3 2 x 0 ,g 0 = = (27.) The stability of the carbonates and hydrogen carbonates down the group [Page: 295] (a) increases. (b) decreases. (c) remains constant. (d) firstly increases and then decreases. (28.) Generally alkali metals have low melting point. Which of the following alkali metals melts as just above the room temperature) [QR c0de, NCERT Exemplar M0dified, Page: 295]