NEET Chemistry The s-Block Elements Questions Solved

Which ion forms a hydroxide highly soluble in water?

(a) Ni2+

(b) K+

(c) Zn2+

(d) Al3+

(b) Alkali metal hydroxides are highly soluble in water.

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What would you observe if excess of dilute NaOH solution is added and shaken with an aqueous solution of aluminium chloride?

(a) A permanent white precipitate is formed immediately

(b) No change at first but a white precipitate is formed on standing

(c) A white precipitate is formed which later dissolves

(d) A green precipitate which turns red on standing in air


 AlCl3 + 3NaOH          Al(OH)3 + 3NaClAl(OH)3 + 3NaOH          Na3AlO3 + 3H2O                                              soluble

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A colourless salt gives violet colour to Bunsen flame and also turns moistured litmus paper blue. It Is:

(a) Na2CO3

(b) KNO3

(c) K2CO3

(d) Cu(OH)2

(c) Violet colour to flame is characteristic of potassium. Also aqueous solution of K2CO3 is alkaline.

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Strongest reducing agent among the following is:

(a) K

(b) Na

(c) Al

(d) Mg

(a) Alkali metals are strongest reducing agents. Also, their reducing power increases down the group.

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When crystal of caustic soda is exposed to air, a liquid layer is deposited because:

(a) crystal melts

(b) crystal loses water

(c) crystal absorbs moisture and CO2

(d) crystal sublimes

(c) NaOH absorbs moisture and CO2 from air to form Na2CO3

2NaOH + CO2          Na2CO3 + H2O2

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Which one of the following is formed on dissolving I2 in aqueous solution of KI ?

(a) KIO4

(b) KIO

(c) KI3

(d) KIO3

(C) KI + I2           KI3

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Which of the following statements is correct for CsBr3?

(a) it is a covalent compound

(b) It contains Cs2+ and Br- ions

(c) It contains Cs+, Br- and Br2 lattice molecules

(d) It contains Cs+ and Br3- ions

(d) CsBr3          Cs++ Br3-

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Hypo is chemically:

(a) Na2S2O3.2H2O

(b) Na2S2O3.3H2O

(c) Na2S2O3.4H2O

(d) Na2S2O3.5H2O

(d) It is chemical formula of Hypo.

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If NaOH is added to an aqueous solution of Zn2+ ions, a white precipitate appears and on adding axcess NaOH, the precepitate dissolves. In this solution zinc exists in the:

(a) cationic part

(b) anionic part

(c) both in cationic and anionic parts

(d) there is no zinc left in the solution


Zn2+ + 2NaOH          2Na+ + Zn(OH)2Zn(OH)2 + 2NaOH         Na2ZnO2 + 2H2OThus, Na2ZnO2 forms 2 Na+ and ZnO22-ions.

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Brine is chemically:

(a) conc. solution of Na2CO3

(b) conc. solution of Na2SO4

(c) conc. solution of NaCl

(d) conc. solution of alum

(c) It is a fact.

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