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21.

When metal 'M' is treated with NaOH , a while gelatinous precipitate 'X' is obtained, which is soluble in excess of NaOH. Compound 'X'  when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal 'M' is

A) Zn

B) Ca

C) Al

D) Fe

22.

The oxidation states of Cr, in [Cr(H2O)6Cl3 , [Cr(C6H6)2] and K2[Cr (CN)2(O)2 (O2 )(NH3)] respectively are

A) +3, +4 and +6

B) +3, +2 and +4

C) +3, 0 and +6

D) +3, 0 and +4

23.

The increasing order of basicity  of the following compound is

A) $(I)<(II)<(III)<(IV)$

B) $(II)<(I)<(III)<(IV)$

C) $(II)<(I)<(IV)<(III)$

D) $(IV)<(II)<(I)<(III)$

24.

How long ( approximate ) should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27.66g of diborane?  (  Atomic weight of B = 10.8μ )

A) 6.4 hours

B) 0.8 hours

C) 3.2 hours

D) 1.6 hours

25.

For 1 molal aqueous solution of the following compounds, which one will show the highest freezing pointt?

A) $[Co( H_{2}O)_{6}]Cl_{3}$

B) $[Co( H_{2}O)_{5}Cl]Cl_{2}.H_{2}O$

C) $[Co( H_{2}O)_{4}Cl_{2}]Cl_{}.2H_{2}O$

D) $[Co( H_{2}O)_{3}Cl_{3}].3H_{2}O$

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