JEE Questions for Chemistry The D And F Block Elements Quiz 8 - MCQExams.com

₆₃Eu and ₇₁Lu are the members of lanthanide series. Due to the lanthanide contraction, the sizes of Eu, Lu and La follow the order Lu < Eu < La.
The element ₃₉Y belongs to the fifth period while Lu belongs to the sixth period, we expect their sizes to follow the order Y < Lu. Hence, the correct
order is
Y³⁺ < Lu³⁺ < Eu³⁺ < La³⁺

Heating rods of iron or steel embedded in charcoal powder is known as case hardening.

In moist air, corrosion of iron takes place in the form of rust (Fe₂O₃ +Fe(OH₃).

Cu(OH)₂ + 4NH₄OH → [Cu(NH₃)₄](OH)₂ + 4H₂O

                                            Soluble

General elect. Config. of transition elements is (n – 1)d^1–10ns^1–2.

Copper can be extracted from malchite CuCo₃ .Cu(OH₂)

Chalcopyrites is copper pyrites (CuFeS₂) from which Cu can be extracted.

German silver is an alloy of Cu (55-60%), Ni (20%), Zn (20 – 25 %).

Luca’s reagent is (ZnCl₂+Conc. HCl) used to distinguish three types of alcohals.

Conc. HNO₃ renders iron passive by forming a thin protective film of Fe₃O₄ on its surface.

Nessler’s reagent is an alkaline solution of K₂ [HgI₄] which contains [HgI₄]^2- ion.

Hg₂Cl₂ + 2NH₄OH → HgNH₂Cl + Hg + NH₄Cl + 2H₂O

Calomel                   Mercuric amino chloride

Dark brown ring formed by nitrates is due to the formation of [Fe(H₂O)₅ NO]²⁺ complex.

When steel is heated in presence of NH₃, iron nitride on the surface of steel is formed which imparts a hard coating. This process is called nitriding.

Fe = 3d⁶4s²; Fe²⁺ = 3d⁶ (4 unpaired electrons);

Fe⁺³ = 3d⁵ (5 unpaired electron); Co = 3d⁷4s²

Co³⁺ = 3d⁷ (3 unpaired electrons); Co³⁺ = 3d⁶ (4 unpaired electrons).