The equivalent weight of K2Cr2O7 in acidic medium is expressed in

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21.

Which of the following statements regarding Lanthanides is false?

  • All lanthanides are solid at room temperature

  • Their usual oxidation state is +3

  • They can be separated from one another by ion-exchange method

  • Ionic radii of trivalent lanthanides steadily increases with increase in atomic number


22.

The correct basicity order of the following lanthanide ions is

  • La3+ > Lu> Ce3+ > Eu3+

  • Ce3+ > Lu3+ > La3+ > Eu3+

  • Lu3+ > Ce3+ > Eu3+ > La3+

  • La3+ > Ce3+ > Eu3+ > Lu3+


23.

Extraction of gold (Au) involves the formation of complex ions X and Y.

Gold ore CN-, H2O, O2Roasting HO- + X Zn Y + Au

X and Y respectively are

  • Au(CN)2- and Zn(CN)42-

  • Au(CN)43- and Zn(CN)42-

  • Au(CN)3- and Zn(CN)62-

  • Au(CN)4- and Zn(CN)3-


24.

The atomic number of cerium (Ce) is 58. The correct electronic configuration of Ce3+ ion is

  • [Xe]4f1

  • [Kr]4f1

  • [Xe]4f13

  • [Kr]4d1


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25.

Cold ferrous sulphate solution on absorption of NO develops brown colour due to the formation of

  • paramagnetic [Fe(H2O)5(NO)]SO4

  • dimagnetic [Fe(H2O)5(NO)]SO4

  • paramagnetic [Fe(H2O)5(NO3)][SO4]2

  • diamagnetic [Fe(H2O)4(SO4)]NO3


26.

Roasted copper pyrite on smelting with sand produces

  • FeSiO3 as fusible slag and Cu2S as matte

  • CaSiO3 as infusible slag and Cu2O as matte

  • Ca3(PO4)2 as fusible slag and Cu2S as matte

  • Fe3(PO4)2 as infusible slag and Cu2S as matte


27.

Cupric compounds are more stable than their cuprous counterparts in solid state. This is because

  • the endothermic character of the 2nd IP of Cu is not so high

  • size of Cu+ is less than Cu2+

  • Cu2+ has stabler electronic configuration as compared to Cu+

  • the lattice energy released for cupric compounds
    is much higher than Cu


28.

The ore chromite is

  • FeCr2O4

  • CoCr2O3

  • CrFe2O4

  • FeCr2O3


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29.

Li occupies higher position in the electrochemical series of metals as compared to Cu since

  • the standard reduction potential of Li+/Li is lower than that of Cu2+ /Cu

  • the standard reduction potential of Cu2+/Cu is lower than that of Li+/Li

  • the standard oxidation potential of Li/Li+ is lower than that of Cu/Cu2+

  • Li is smaller in size as compared to Cu


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30.

The equivalent weight of K2Cr2O7 in acidic medium is expressed in terms of its molecular weight (M) as

  • M/3

  • M/4

  • M/6

  • M/7


C.

M/6

In acidic medium,   K2Cr2+6O7  Cr3+Equivalent weight of K2Cr2O7= Molecular weight Change in oxidation state of Cr                =M2(6-3)=M6


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