Class 12 Chemistry - Chapter The d-and f-Block Elements NCERT Solutions | In the series Sc (Z = 21) to Zn (Z = 30)

Explain why Cu⁺ ion is not stable in aqueous solutions?

Silver atom has completely filled d orbitals (4d10) in its ground state. How can you say that it is a transition element?

The E^θ(M²⁺/M) value for copper is positive (+0.34V). What is possibly the reason for this? (Hint: consider its high Δ_aHV and low Δ_hydHV)

How would you account for the following:

(i) Of the d⁴ species, Cr²⁺ is strongly reducing while manganese (III) is strongly oxidising.

(ii) Cobalt (II) is stable in aqueous solution but in the presence of complexing reagents it is easily oxidised.

(iii) The d¹ configuration is very unstable in ions.

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

Which is a stronger reducing agent Cr²⁺ or Fe²⁺ and why?

Explain giving reasons:

(i) Transition metals and many of their compounds show paramagnetic behaviour.

(ii) The enthalpies of atomisation of the transition metals are high.

(iii) The transition metals generally form coloured compounds.

(iv) Transition metals and their many compounds act as good catalyst.

Give examples and suggest reasons for the following features of the transition metal chemistry:

(i)The lowest oxide of transition metal is basic, the highest is amphoteric/acidic.

(ii)A transition metal exhibits highest oxidation state in oxides and fluorides.

(iii) The highest oxidation state is exhibited in oxoanions of a metal.

Predict which of the following will be coloured in aqueous solution?

Ti³⁺, V³⁺, Cu⁺, Sc³⁺, Mn²⁺, Fe³⁺ and Co²⁺.

Give reasons for each.

Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?

For the reaction R → P, the concentration of a reactant changes from 0.03 M to 0.02 M in 25 minutes. Calculate the average rate of reaction using units of time both in minutes and seconds.

Write the formulas for the following coordination compounds:

(i) Tetraamminediaquacobalt (III) chloride

(ii) Potassium tetracyanonickelate(II)

(iii) Tris(ethane-1,2-diamine) chromium(III) chloride

(iv) Amminebromidochloridonitrito-N-platinate(II)

(v) Dichloridobis(ethane-1,2-diamine)platinum(IV) nitrate

(vi) Iron(III) hexacyanoferrate(II)

(i) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N

(ii) Write IUPAC names of all the isomers.

(iii) What type of isomerism is exhibited by different pairs of amines?

Why are solids rigid?

Write any two characteristics of Chemisorption.

Write the structures of the following compounds.

(i) α-Methoxypropionaldehyde

(ii) 3-Hydroxybutanal

(iii) 2-Hydroxycyclopentane carbaldehyde

(iv) 4-Oxopentanal

(v) Di-sec-butyl ketone

(vi) 4-Fluoroacetophenone

Which of the ores mentioned in Table 6.1 can be concentrated by magnetic separation method?

Why are pentahalides more covalent than trihalides?

Glucose or sucrose are soluble in water but cyclohexane or benzene (simple six membered ring compounds) are insoluble in water. Explain.

Write structures of the following compounds:

(i) 2-Chloro-3-methylpentane

(ii) 1-Chloro-4-ethylcyclohexane

(iii) 4-tert. Butyl-3-iodoheptane

(iv) 1,4-Dibromobut-2-ene

(v) 1-Bromo-4-sec. butyl-2-methylbenzene

The decomposition of NH₃on platinum surface is zero order reaction. What are the rates of production of N₂and H₂if k = 2.5 x 10^-4mol^-1L s^-1?

Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl palmitate. Structural formulae of these compounds are given below.

(i) (C₁₅H₃₁COO)₃ C₃H₅ - Glyceryl palmitate

(ii)(C₁₇H₃₃COO)₃ C₃H₅ - Glyceryl oleate

The rate constant for the decomposition of N₂O₅ at various temperatures is given below:

Draw a graph between ln k and 1/T and calculate the values of A and E_a.

Predict the rate constant at 30 º and 50 ºC.

How is 'cast iron' different from 'pig iron"?

For the reaction:

2A + B → A₂B

the rate = k[A][B]²with k= 2.0 x 10^-6mol^-2L²s^-1. Calculate the initial rate of the reaction when [A] = 0.1 mol L^-1, [B] = 0.2 mol L^-1. Calculate the rate of reaction after [A] is reduced to 0.06 mol L^-1.

How many ions are produced from the complex Co(NH₃)₆Cl₂ in solution?

(i) 6

(ii) 4

(iii) 3

(iv) 2

Why cannot aromatic primary amines be prepared by Gabriel phthalimide synthesis?

Which alkyl halide from the following pairs would you expect to react more rapidly by an S_N2 mechanism? Explain your answer.

Which one of the following has the highest dipole moment?

(i) CH₂Cl₂

(ii) CHCl₃

(iii) CCl₄

Calculate the molarity of each of the following solutions:

(a)30 g of Co(NO₃)₂. 6H₂O in 4.3 L of solution

(b)30 mL of 0.5 M H₂SO₄ diluted to 500 mL.