Chemistry M.C.Q [1M]

3. Occlusion

Explanation:

When adsorption happens on metals, it is called occlusion. Occlusion happens on a variety of metals, including iron, platinum and palladium, but hydrogen gas is the only adsorbate.

2. Liquid.

Explanation:

Gallium is in liquid state at room temperature. The melting point of gallium is 303K.

2. The ionic radii of trivalent lanthanides steadily increases with increase in atomic number

Explanation:

The ionic radii of trivalent lanthanides steadily decreases with increase in atomic number due to lanhanide contraction.

3. V³⁺

4. Transitional elements

Explanation:

Transitional elements form coloured salts due to the presence of unpaired electrons of d-orbital.

3. Tm

Explanation:

Tm (thulium) atomic no. = 69 belongs to Lanthanoids (4f) series.

2. Paramagnetic.

Explanation:

Most of trasition metls have unpaired electron (d-configuration) in their electronic configuration so they are paramagnetic in nature.

2. Actinoids

Explanation:

The actinoids are radioactive elements and the earlier members have relatively long half-lives.

The most common and known element is Uranium, which is used as nuclear fuel when its converted into plutonium, through a nuclear reaction.

3. Th

Explanation:

Lu, Gd and La belongs to lanthanide series and Th belongs to actinide series.

1. Zr, Hf

3. Zn

Explanation:

Zinc is not a transition element due to complete d-orbital.

1. Mo

Explanation:

Among given metals, molybdenum is used in X-rays tube. In medical X-ray tubes the target is usually tungsten or a more crack-resistant alloy of rhenium (5%) and tungsten (95%), but sometimes molybdenum is used for more specialized applications, such as when softer X-rays are needed as in mammography.

4. Prevent action of oxygen and water.

Explanation:

Iron sheets are covered with a layer of Zinc i.e. galvanized mainly to prevent action of oxygen and water.

1. A

1. Cu(II) is more stable

Explanation:

Cu (II) is more stable due to greater effective nuclear charge of Cu (II).

2. Cu²⁺ oxidizes iodide to iodine.

Explanation:

All Cu(II) halides are known except the iodine because Cu²⁺ oxidizes iodine to iodine.

2Cu²⁺+ 4I⁻¹ → 2CuI_(S)​ + I_2​.

4. Hg

Explanation:

Among the metals, interatomic forces are probably the weakest in Hg.

This can be understand from the fact that Hg is liquid whereas Cu, Ag and Zn are solids at room temperature.

2. 28

Explanation:

E.C of M : [Ar]4s²3d⁸

E.C of M²⁺ : [Ar]4s⁰3d⁸

Total electrons = 28 = atomic number.

2. Light green.

Explanation:

Colour of Fe²⁺ is light green.

Due to this many salts having Fe²⁺ ion are also green in colour.

For ex: FeSO_4​

4. Cu

Explanation:

On moving across the period in the periodic table the atomic radii of the element decreases towards right that is why density increases towards right in a period.

2. Cu

Explanation:

The noble metals are those metals that are resistant to corrosion and oxidation in moist air, unlike most base metals. The noble metals are most commonly considered to be ruthenium, rhodium, palladium, silver, platinum and gold. Copper is not considered to be a noble metal.

1. Co⁺²

Explanation:

Co⁺² = [Ar]3d⁷n = 3  attracted by a magnetic field due to presence of 3 unpaired electron.

1. 2

Explanation:

Fe² + (z = 26) = [Ar] 3d⁶

Cr² + (z = 24) = [Ar] 3d⁴

2. 5f

Explanation:

5f sub shell is filled up progressively in actinoids.

3. Fluorides and Oxides.

Explanation:

The highest oxidation states of transition metals are found in fluorides and oxides since fluorine and oxygen are the most electronegative elements and small in size.

4. Actinides.

Explanation:

Actinides are also called the 5f series.

Filling up of the 5f orbitals after actinium (Z = 89) gives the 5f-inner transition series known as the actinoid series.

2. II A group

Explanation:

Zinc belongs to IIB and it closely resembles IIA because of the completely filled valence orbitals. The reason is in IIA group all the elements have completely filled s-orbital while in IIB group the elements have completely filled s orbital along with d-orbital.

2. Low ionization energy.

4. Within the d-orbitals.

Explanation:

Colour in transition series metal compounds arises due to two types of transitions. they are:

(a) Charge transfer transitions [Ligand-to-metal charge transfer (LMCT), Metal-to-ligand charge transfer]

(b) d−d transition

In transition metal complexes, all the d− orbitals do not possess same energy. So, electrons can jump from a lower energy d− orbital to a higher energy d− orbital, by absorbing energy. When it returns to the ground state, excess energy is released, and a corresponding wavelength is found in the visible region.

3. Both (A) and (B).

Explanation:

The property seen in f-block elements are Lanthanoid contraction and Actinide contraction. Lanthanide contraction is a term used in chemistry to describe the greater than expected decrease in ionic radii of the elements in the lanthanide series.

1. 9 - 18

3. U

Explanation:

Uranium belongs to actinide series. Yttrium and tantalum belons to d-block. Lutetium belongs to lanthanide series.

4. Unpaired electrons.

4. CuF₂

Explanation:

Cu²⁺ has 1 unpaired electron in CuF₂, hence, it is coloured in solid state.

3. Promethium.

Explanation:

Promethium is a lanthanoid element with the symbol Pm and atomic number 61. All of its isotopes are radioactive. Gadolinium, holmium and neodynium are lanthanoids but are not radio active.

2. Throium.

Explanation:

Monazite is a prosphate material containing rare earth metals. It is reddish in colour. It is an important ore  for throium, lanthanum, cerium.

4. Ionic radii of trivalent lanthanides steadily increase with an increase in the atomic number.

Explanation:

Ionic radii decreases with increasing atomic number in Lanthanide series. So, the ionic radii of trivalent Lanthanide will also follow the same property.

1. Electronic configuration.

Explanation:

Lanthanides and actinides resemble in electronic configuration:

(n−2)f¹⁻¹⁴(n−1)d¹⁻¹⁰ns¹⁻²

2. Ni²⁺

Explanation:

Only Ni⁺² has incomplete d-orbitals d⁸ so it is colourfull. Sc⁺³, Ti⁺⁴ ; d0 configuration and Zn⁺², d¹⁰ configuration so they are colourless.

1. Adopt multiple oxidation states and to form complexes.

Explanation:

Transition metals have partially filled d- orbitals so they can easily withdraw the electrons from the reagents or give electrons to them depending on the nature of the reaction. They also have a tendency to show large no. of oxidation states and the ability to form complexes which makes them a good catalyst.

1. White

Explanation:

Cu⁺ compounds are generally colourless (white). The electronic configuration is 3d¹⁰4s⁰. So there is no unpaired electron present in the ion. So the electronic transition between two energy levels t_2g​ and e_g​ (responsible for the colour of transition metals) is not possible.