TRANSITION ELEMENT QUIZ-9

Q1. The process used in obtaining metallic silver from argentite is:

•  Fused mixture of Ag_2 S and KCl is electrolysed
•  Ag_2 S is reduced with CO
•  Ag_2 S is roasted to Ag_2 O which is reduced with C
•  Treating with NaCN solution followed by metal displacement with zinc

Solution

Q2.The actinoids showing +7 oxidation state are

•  U, Np
•  Np, Pu
•  Pu, Am
•  Am, Cm

Solution
Np and Pu in NpO_3^+ and PuO_3^+ oxocations show +7 oxidation state which are not so stable

Q3.  Mercury is purified by:

•   Solidifying
•  Electrolytic method
•  Treatment with dil. HNO_3
•  Distillation in vacuum

Solution
Hg has low b.p. like other members of gp. 12.

Q4. Non-stoichiometric compounds are formed by:

•  Alkali metals
•  More than one of the above elements
•  Noble gases
•  Transition elements

Solution
A characteristic of transition elements.

Q5.The flux used in the smelting of copper is:

•  Silica
•  Coke
•  Magnesia
•  Limestone

Solution
 The gangue of FeO comes out as slag with acidic flux SiO_2.

Q6. Percentage of nickel in nickel steel is:

•  1.5%
•  3.5%
• 6.5%
•  8.5%

Solution
Ni-steel contains 3.5% Ni and is used in making cables, automobiles and aeroplane parts, armour plates, propeller shafts, etc.

Q7.KI and CuSO_4 solutions on mixing produce

•  Cu_2 I_2 +K_2 SO_4
•  CuI_2+ I_2+ K_2 SO_4
•  Cu_2 I_2+I_2+K_2 SO_4
•  CuI_2+ K_2 SO_4

Solution
CuSO_4+2KI⟶ Cul_2+ K_2 SO_4 2 Cul_2 ⟶ Cu_2 I_2 + I_2 cuprous iodide white ppt.

Q8.Lanthanides are

•  14 elements in the sixth period (atomic no. = 90 to 103) that are filling 4fsub level.
•  14 elements in the sixth period (atomic no. = 58 to 71) that are filling 4f sub-level.
•  14 elements in the seventh period (atomic no. = 90 to 103) that are filling 5f sub level.
•  14 elements in the seventh period (atomic no. = 58 to 71) that are filling 4f sub-level.

Solution
Lanthanides are the 14 elements of IIIB group and sixth period (At. no.=58 to 71) that are filling 4f-subshell of antipenultimate shell from 1 to 14 . Actually, they are placed below the Periodic Table in horizontal row as lanthanide series.

Q9.A transition element X has the configuration [Ar]d^4 in its +3 oxidation state. Its atomic number is

•  19
•  22
•  26
•  25

Solution
Given, X=[Ar]d^4 ∵ The complete configuration of the ion, X^(3+) =1s^2,2s^2 ,2p^6,3s^2 3p^6,3d^4 ∴ X= 1s^2,2s^2 ,2p^6,3s^2,3p^6 ,3d^5 4s^2 ∴ The atomic number of the element is 25 and the element is Mn.

Q10. Which of the following is used for sterilization of surgical instruments?

•  ZnO
•  HgCl_2
•  ZnCl_2
• Hg_2 Cl_2

Solution
Due to poisonous nature of HgCl_2, its 0.1% solution is used as antiseptic for sterilizing hands and instruments in surgery.