Chemistry M.C.Q (1 Marks)

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.

2. +3

Explanation:
In the lanthanoids, La(II) and Ln(III) compounds are predominant species. However, occasionally +2 and +4 ions in solution or in solid compounds are also obtained. This irregularity (as in ionisation enthalpies) arises mainly from the extra stability of empty, half-filled or filled f subshell.

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. 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.

2. Lutetium.

Explanation:
Lutetium is the last element of the Lanthanides, so it will have the smallest ionic radius due to Lanthanide contraction.

4. Incomplete (n−1)d subshell.

Explanation:
Any compound or ion showing colour is due to presence of unpaired electron. Transition metal compounds have incomplete (n-1)d sub shell and because of that they have unpaired electron and  thus they show colour.

Since they react with acid as well as base.

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

4. Transitional elements

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

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. Au

Explanation:
As shown in image, Gold has 2 electrons in level 1, 8 electrons in level 2, 18 in level 3, 32 in level 4, 18 in level 5 and 1 electron in level 6. Gold is having 1 eletcron in last level, so it can lost 1 electron to complete their valency or it can also gain 1 electron thus 2 electron will come in outer cell and will complete the last level.

3. Tm

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

1. Th, Pa, U

Explanation:
Th(thorium), Pa(proactinium) and U(uranium) belongs to actinoid series.
CePr, Nd are lanthanoids.
Ba, La, Hf belongs to the sixth period.
Pt, Au, Ag are transition elements.

1. A microcell.

Explanation:
The above-given salt-solution is purified electrolytically by adding carbonaceous matter which acts as a microcell.

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. N > O > P > S

Explanation:
Moving left to right within a period or upward within a group, the first ionization energy generally increases with a few discrepancies (aluminum and nitrogen group).
Nitrogen group to oxygen group, I.P. decreases instead of increasing because of the stable half-filled configuration of nitrogen family.
N(1400) > O(1313) > P(1011) > S(999)

1. A

2. Manganese dioxide.

Explanation:
Glass is decolourised by manganese dioxide.

1. The name of californium was derived from the name of the place.

Explanation:
The name of californium was derived from the name of the state and University of California.

1. Fe

Explanation:
According to reactive series, Most reactive metal is Iron (Fe)
Reactivity order is: Fe > Ni > Au > Pt

3. (n−1)d and ns orbits

Explanation:
The ability of the transition metals to exhibit variable valency is generally attributed to the availability of more electrons in the (n−1)d orbitals which are closer to the outermost ns orbital in energy levels.

4. Silver.

Explanation:
A silver halide (or silver salt) is one of the chemical compounds that can form between the element silver and one of the halogens. Silver halides are used in photographic film and photographic paper, including graphic art film and paper, where silver halide crystals in gelatin are coated on to a film base, glass or paper substrate. The gelatin is a vital part of the emulsion as the protective colloid of appropriate physical and chemical properties.

2. Ionic radius of the series.

Explanation:
The Lanthanoid contraction refers to decrease in the ionic radius of the series. It is a reduction in atomic/ionic size with increase in atomic number. This is due to poor shielding of 4f electrons.

1. Np

Explanation:
The transuranic elements are the chemical elemnts with atomic numbers greater than 92 (the atomic number of Uranium). Neptunium is the first element of transuranic series with atomic number 93..

3. Both have similar atomic radius.

Explanation:
The almost identical radii of Zr (160pm) and Hf (159pm), a consequence of the lanthanoid contraction, account of their occurrence together in nature and for the similar physical and chemical properties.

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.

2. High ionization potential and high melting point.

Explanation:
Transition metals are less reactive relative to I and II group due to higher ionization potential and high melting point (due to greater no of bonding electrons).

4. Ability to adopt multiple oxidation states and their complexing ability.

Explanation:
The catalytic activity of the transition metals and their compounds is ascribed to their ability to adopt multiple oxidation states and their complexing ability.
Catalysis at a solid surface involve the formation of bonds between reactant molecules and atoms of the surface of the catalyst (first row transition metals utilise 3d and 4s electrons for bonding).
This has the effect of increasing theconcentration of the reactants at the catalyst surface and also weakening of the bonds in the reacting molecules (the activation energy is lowering).
Also because the transition metal ions can change their oxidation states, they become more effective as catalysts. For example, iron(III) catalyses the reaction between iodide and persulphate ions.

2. Paramagnetic.

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

1. Ni

Explanation:
Nickel is used as catalyst in oil industry. It is used in catalytic hydrogenation.

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.

2. F-block.

Explanation:
A reduction in atomic size with increase in atomic number is a characteristic of f-block elements.
This is due to poor shielding of f electrons. The extent of actinoid contraction is greater than lanthanoid contraction. With increase in atomic number i.e. in moving down a group, the number of the principal shell increases and therefore, the size of the atom increases. But in case of f ­block elements there is a steady decrease in atomic size with increase in atomic number due to lanthanide contraction. As we move through the lanthanide series, 4f electrons are being added one at each step.
The mutual shielding effect of f electrons is very little. This is due to the shape of the f ­orbitals. The nuclear charge, however increases by one at each step. Hence, the inward pull experienced by the 4f electrons increases. This causes a reduction in the size of the entire 4fn shell.

4. Ni is used as catalyst in the manufacture of ammonia in the redox reaction.

Explanation:
known as Born-Haber's cycle catalyst Fe is used not Ni.

3. 8

Explanation:
From structure, it is clear that it has 8 Cr−O bond, out of which 6 Cr−O bonds are equal.

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.

2. Fe, Co, Ni

Explanation:
Ferromagnetic substances are those which get strongly magnetized in the presence of a magnetic field.
These substances have domains that get aligned in the magnetic field, thus increasing their strength.
These are strongly attracted by a magnet.
Examples include iron, cobalt, nickel, etc.

3. Transition metal.

Explanation:
Transition metals can form unstable intermediate products with suitable reactants. These intermediate products lower the activation energy of the reaction which makes the reaction faster. So, transition elements are the most efficient catalysts.

4. All of the above.

Explanation:
Transition metals  has incompletely filled d orbital. They have vacant orbitals to accept coordination bond. Complex compounbs are those in which the metal ion bind a number of anions or neutral molecules giving complex species with characteristics properties. The transition metals form a large no. of complex compounds.
This is due to the comparatively smaller size of the metal ions,their high ionic charges and the availability of d orbitals for bond formation.

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.

4. Ability to adopt multiple oxidation states and their complexing ability.

Explanation:
The catalytic activity of the transition metals and their compounds is ascribed to their ability to adopt multiple oxidation states and their complexing ability. Catalysis at a solid surface involve the formation of bonds between reactant molecules and atoms of the surface of the catalyst (first row transition metals utilise 3d and 4s electrons for bonding). This has the effect of increasing theconcentration of the reactants at the catalyst surface and also weakening of the bonds in the reacting molecules (the activation energy is lowering). Also because the transition metal ions can change their oxidation states, they become more effective as catalysts. For example, iron(III) catalyses the reaction between iodide and persulphate ions.

2. By treating nickelaluminium alloy with dilute NaOH.

Explanation:
Raney nickel, s solid catalyst composed of fine grains of a nickel Aluminium alloy which is used in many industrial process. It is obtained by treating nickel-Aluminium alloy with dilute NaOH.

3. 90 to 103

Explanation:
Second inner transition elements are from thorium to lawrencium, i.e., from atomic numbers 90 to 103.

1. 9 - 18

2. Size of the ions.

Explanation:
The separation of Lanthanoids by ion-exchange method is based on the size of the ions.
Separation can also be attained by size exclusion or gel permeation chromatography.

2. Transition elements.

Explanation:
In transition metals, (n−1) d and ns electrons have nearly same energy level. Hence, most of these electrons take part in chemical bonding. Hence, transition metals show variable valency.

3. The presence of unpaired electrons.

Explanation:
Any metal or ion having unpaired electron will show paramagnetism.

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. Transition metal complexes reflect the complimentary colour of absorbed colour.

Explanation:
During this d-d transition process, the electrons absorb certain energy from the radiation and emit the remainder of energy as colored light. The color of ion is complementary of the color absorbed by it.

3. Th

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

3. U

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

1. Zr, Hf

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.

4. 0

Explanation:
Magnetic moment of diamagnetic substance is zero.

4. f

Explanation:
In inner transition elements, the differentiating electron enters into f orbitals. So these elements are called f-block elements.
The ‘f’ – block elements are also known by the name of inner transition elements. In these elements, the last electron usually enters the penultimate i.e. (n – 2) f of the orbital.

4. Unpaired electrons.

• Ionic radius of the series.
• Explanation:
  Lanthanide contraction is a term used to describe the greater than expected decrease in ionic radii of the elements in the lanhtanide series from atomic number 57 i.e. lanthanum to 71 lutetium, which results in smaller than otherwise expected ionic radii for the subsequent elements starting with 72 i.e. hafnium.

4. Cobalt oxide.

Explanation:
Cobalt oxide is used to obtain blue coloured glass.

2. Incomplete d - orbitals.

Explanation:
D-block elements show variable valency due to their incomplete d-orbitals.

3. D-block elements.

Explanation:
The tendency towards complex formation is maximum in d−block elements as they have maximum vacant orbitals and thus shows variable oxidation state.

4. They are chemically very reactive.

Explanation:
Interstitial compounds are chemically inert.

1. Uranium - 235

Explanation:
Nuclear fuel is a substance that is used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission.
Most nuclear fuels contain heavy fissile elements that are capable of nuclear fission, such as uranium - 235 or plutonium - 239. When the unstable nuclei of these atoms are hit by a slow-moving neutron, they split, creating two daughter nuclei and two or three more neutrons. These neutrons then go on to split more nuclei. This creates a self-sustaining chain reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon.

4. Ni

Explanation:
Non-precious metal catalysts, especially those based on nickel (such as Raney Nickel and Urushibara Nickel) are generally used as catalyst in the hydrogenation of oils. Palladium can also be used but it is very costly.

3. Atomic radius.

Explanation:
Due to the poor shielding effect of 4f electrons the outer electrons experience more attractive force from nucleus.
Due to this attraction, the size of elements contracts. This contraction is known as lanthanide contraction. In this way, lanthanide contraction is related to atomic radii.

2. Vacant d-orbitals.

Explanation:
The catalytic activity of transition elements is ascribed to their ability to adopt multiple oxidation states and to form complexes.

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.

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. U

Explanation:
Uranium belongs to actinoid series of elements. Neodymium and Samarium belongs to lanthanide series. Gold belongs to d-block.

1. A whiter 'white'

Explanation:
Titanium oxide is added in intercor paints for walls of room, halls and galleries to give a whiter white.

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.

3. Mn (Z = 25)

Explanation:
The maximum oxidation state is the number of 4s electrons plus the number of unpaired 3d electrons.

3. Tm

Explanation:
Thulium (Tm) has atomic number 69, and actinoid series has elements from atomic number 90-103.
Thulium belongs to lanthanoid series.

2. Low ionization energy.

2. Completely filled d-level in Cu(I).

Explanation:
In copper (I) ion there are no vacant d orbitals as it is diamagnetic. Copper(I) ion being less charged has small ligand field effect and the transition is in the infrared region in which no color is perceived by human eye.

4. Transition elements.

Explanation:
Elements which exhibit both vertical and horizontal similarities are transition elements. They show vertical similarity because of same electronic configuration. They show horizontal similarity because of similar size.

2. Transition elements.

Explanation:
Transition elements have vacant d orbitals and the energy gap between d orbitals is very less. So transition elements exhibit variable oxidation state and form coloured ions as these elements emit radiations due to excitation of d electrons.

3. All of their ions are colourless.

Explanation:
Properties of transition elements include:

1. Have large charge/ radius ratio.
2. Are hard and have high densities.
3. Have high melting and boiling points.
4. Form compounds which are often paramagnetic.
5. Show variable oxidation states.
6. Form coloured ions and compounds.
7. Form compounds with profound catalytic activity.
8. Form stable complexes.

3. D-block

Explanation:
D-block metals, e.g. Ni, Pt, Fe, etc, are used as catalysts.

4. Actinium and Lawrencium.

Explanation:
We have 15 elements in actinides. They are from atomic number 89 to 103 Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium, Lawrencium. Hence, from these list we could say that Actinium is the first and Lawrencium is the last element in actinides.

4. Nb - Ta

Explanation:
Chemical twins are those in which the properties of some elements are same. Atomic size of Zr and Hf , Nb and Ta are similar. This is due to lanthanide contraction.

3. Zn

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

1. Sc > Y > La

Explanation:
IP values of Sc, Y and La are in the order Sc > Y > La On moving down the group, the IP values decreases as the effective nuclear charge decreases due to poor shielding by inner electrons.

2. 5f

Explanation:
5f sub shell is filled up progressively in actinoids.

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. F - block element

Explanation:
The two rows that are generally placed underneath the main Periodic Table are called the lanthanide series and the actinide series.
These two rows are produced when electrons are being added to f orbitals.

4. Chromium.

Explanation:
Most of the chromium compounds are coloured due to excitation of an electron from a lower energy d-orbital to higher energy d-orbital, the energy of excitation corresponds to the frequency of light absorbed. This frequency lies in a visible region. The colour observed corresponds to the complementary colour of light absorbed.

3. They have free electrons in outer energy levels.

Explanation:
Transition metals have free electrons in outer energy levels because d-orbitals shields poorly and due to this they acts as good conductor of electricity.

A

C

A