In chromic acid, (CrO₃), Cr has d^O configuration but it is bright orange coloured solid, why?

Calculate the spin only magnetic moment of Iron present in the following compound.
[Fe(H₂O)5NO]²⁺

Explain: Transition metals have high melting and boiling points.

Which metal in the first series of transition metals exhibits +1 oxidation state most frequently and why?

Why are Cr²⁺ reducing and Mn³⁺ oxidising when both have d⁴ configuration?

Chromium is used extensively in steel alloys. It is extracted from its ore chromite (FeCr₂O₄), which contains chromium in +3 oxidation state.
(i) Give the electronic configuration of the elements iron and chromium.
(ii) What is the oxidation state of iron in chromite?

The outer electronic configurations of two members of the lanthanoid series are as follows: 4f¹ Sd¹ and 4f⁷ 5d^o 6s². What are their atomic numbers? Predict the oxidation states exhibited by these elements in their compounds.

Compare the chemistry of the actinoids with that of lanthanoids with reference to the following :
(i) Electronic configuration
(ii) Oxidation states
(iii) Chemical reactivity

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.

(a) Comlete the following chemical equations for reactions in aqueous media:
(i) Cr₂O₇^2-+H⁺+Fe2+ \(\longrightarrow \)
(ii) MnO₄^-+I^-+H⁺\(\longrightarrow \)
(b) How many unpaired electrons are present in Mn²⁺ ion (At. no. of Mn =25)? How does it influence magnetic behaviour of Mn²⁺ ions?

Write the electronic configurations of the elements with the atomic numbers 61, 91, 101, and 109.

In the following reactions, ZnO is respectively acting as a/an
\((i) \mathrm{ZnO}+\mathrm{Na}_{2} \mathrm{O} \longrightarrow \mathrm{Na}_{2} \mathrm{ZnO}_{2} \)
\((ii) \mathrm{ZnO}+\mathrm{CO}_{2} \longrightarrow \mathrm{ZnCO}_{3}\)

Knowing that  the chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements is incorrect ?

Which of the following exhibits only +3 oxidation state ?

Gadolinium belongs to 4 f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium ?

KMnO₄ on heating to red hot gives

Read the passage given below and answer the following questions:
The transition elements have incompletely filled d-subshells in their ground state or in any of their oxidation states. The transition elements occupy position in between s- and p-blocks in groups 3-12 of the Periodic table. Starting from fourth period, transition elements consists of four complete series : Sc to Zn, Y to Cd and La, Hf to Hg and Ac, Rf to Cn. In general, the electronic configuration of outer orbitals of these elements is (n - 1) d^1-10 ns^1-2. The electronic configurations of outer orbitals of Zn, Cd, Hg and Cn are represented by the general formula (n - 1)d¹⁰ n². All the transition elements have typical metallic properties such as high tensile strength, ductility, malleability. Except mercury, which is liquid at room temperature, other transition elements have typical metallic structures. The transition metals and their compounds also exhibit catalytic property and paramagnetic behaviour. Transition metal also forms alloys. An alloy is a blend of metals prepared by mixing the components. Alloys may be homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other.
The following questions are multiple choice questions. Choose the most appropriate answer :
(i) Which of the following characteristics of transition metals is associated with higher catalytic activity?

(a) High enthalpy of atomisation	(b) Variable oxidation states
(c) Paramagnetic behaviour	(d) Colour of hydrated ions

(ii) Transition elements form alloys easily because they have

(a) same atomic number	(b) same electronic configuration
(c) nearly same atomic size	(d) same oxidation states.

(iii) The electronic configuration of tantalum (Ta) is

(a) \([\mathrm{Xe}] 4 f^{0} 5 d^{1} 6 s^{2}\)	(b) \([\mathrm{Xe}) 4 f^{14} 5 d^{2} 6 s^{2}\)
(c) \([\mathrm{Xe}] 4 f^{14} 5 d^{3} 6 s^{2}\)	(d) \(\left[\mathrm{Xe}\left]4 f^{14} 5 d^{4} 6 s^{2}\right.\right.\)

(iv) Which one of the following outer orbital configurations may exhibit the largest number of oxidation states?

(a) 3d54s1

(b) 3d54s2

(c) 3d24s2

(d) 3d34s2

Read the passage given below and answer the following questions:
The f-block elements are those in which the differentiating electron enters the (n -2) forbital. There are two series of f-block elements corresponding to filling of 4f and 5f-orbitals. The series of 4f- orbitals is called lanthanides. Lanthanides show different oxidation states depending upon stability of f⁰, f⁷ and f¹⁴ configurations, though the most common oxidation states is +3. There is a regular decrease in size of lanthanides ions with increase in atomic number which is known as lanthanide contraction.
The following questions are multiple choice questions. Choose the most appropriate answer:
(i) The atomic numbers of three lanthanide elements X, Y and 2 are 65, 68 and 70 respectively, their Ln³⁺ electronic configuration is

(a) 4f8, 4f11, 4f13

(b) 4f11, 4f8 , 4f13

(c) 4fo, 4f2, 4f11

(d) 4f3, 4f7, 4f9

(ii) Lanthanide contraction is observed in

(a) Gd

(b) At

(c) Xe

(d) Te

(iii) Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state.

(a) Cerium (Z = 58)

(b) Europium (Z = 63)

(c) Lanthanum (Z = 57)

(d) Gadolinium (Z = 64)

(iv) Identify the incorrect statement among the following.

(a) Lanthanojd contraction is the accumulation of successive shrinkages.

(b) The different radii of Zr and Hf due to consequence of the lanthanoid contraction.

(c) Shielding power of 4f electrons is quite weak.

(d) There is a decrease in the radii of the atoms or ions as one proceeds from La to Lu.

Assertion: Cuprous salts are diamagnetic.
Reason: Cu⁺ has 3d filled subshell.
Codes:
a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
b) Both assertion and reason are true but the reason is not the correct explanation of assertion.
c) Assertion is not true but the reason is true.
d) Both assertion and reason are false.

Assertion: Zinc is used in the galvanisation of iron.
Reason: Its coating on iron articles increases their life by protecting them from rusting.
​​​​​​​Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.