TRANSITION ELEMENT QUIZ-2

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Q1. The lanthanide contraction is responsible for the fact that:

•  Zr and Zn have the same oxidation state
•  Zr and Nb have similar oxidation state
•  Zr and Y have about the same radius
•  Zr and Hf have about the same radius

Solution
Lanthanide contraction, cancels almost exactly the normal size increase on descending a group of transition elements, thus Nb and Ta, Zr and Hf have same covalent and ionic radii.

Q2.Lithopone, a white pigment, consists of:

•  Al_2 O_3 and CaCO_3
•  ZnS and BaSO_4
•  PbS and MgO
•  BaS and PbSO_4

Solution
Lithopone is used as white pigment and contains ZnS+BaSO_4.

Q3.  The equilibrium Cr_2 O_7^(2-)+2e⇌〖2CrO〗_4^(2-):The equilibrium Cr_2 O_7^(2-)+2e⇌〖2CrO〗_4^(2-):

•   Does not exist
•  Exists in neutral medium
•  Exists in acidic medium
•  Exists in basic medium

Solution
2e+Cr_2 O_7^(2-)⇌2CrO_4^(2-) exists in basic medium.

Q4. Which one of the following exist in the oxidation state other than +3?

•  Ga
•  Al
•  B
•  Ce

Solution
Boron(B), aluminium(Al) and gallium, (Ga) are present in IIIA group. They show +3 oxidation state. While cerium(Ce) is a lanthanoid. It is present in lanthanide series. It shows +3 and +4 oxidation states.

Q5.Pig iron:

•  Contains carbon and other impurities
•  Is pure form of iron
•  Is same as wrought iron
•  Is same as steel

Solution
 In Bessemer’s converter impurities of C, Mn, Si, P in pig iron are oxidized to produce steel..

Q6. Pure conc. HNO_3 makes iron passive as the surface is covered with protective layer of:

•  Fe(NO_3 )_3
•  Fe_3 O_4
• FeO
•  Fe_2 O_3

Solution
μ_eff value of 1.73 BM corresponds to one unpaired electron. Ti^(3+)=3d^1 (Ti=[Ar]3d^2 4s^2)

Q7.Which metal is not used for making coins?

•  Gold
•  Silver
•  Tungsten
•  Nickel

Solution
It is a fact. Rest all are coinage metals.

Q8.The catalyst used for the hydrogenation of vegetable oils for making margarine is:

•  Zn
•  Ni
•  Na
•  Cu

Solution
〖Oil┬((Unsaturated))+H_2 □(→┴Ni ) Ghee┬((Saturated))〗⁡

Q9.Which compound cannot be prepared?

•  Zn(OH)_2
•  Cd(OH)_2
•  HgCl_2
•  Hg(OH)_2

Solution
Hg(OH)_2 does not exist

Q10. Bronze is a mixture of

•  Pb + Sn
•  Cu + Sn
•  Cu + Zn
• Pb + Zn

Solution
Bronze is a mixture of Cu and Sn.