Test: The D And F-Block Elements 2 - From Past 28 Years Questions


35 Questions MCQ Test Chemistry 28 Years Past year papers for NEET/AIPMT Class 12 | Test: The D And F-Block Elements 2 - From Past 28 Years Questions


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QUESTION: 1

Which of the following metals corrodes readily in moist air ? [1980]

Solution:

In moist air, corrosion of iron takes place in the form of rust (Fe2O3 + Fe(OH)3) . As iron is most reactive among all.

QUESTION: 2

Which one of the following is an ore of silver ? [1983]

Solution:

Argentite or silver glance (Ag2S) is an ore of Ag.

QUESTION: 3

The oxidation state of Cr in K2Cr2O7 is[1988]

Solution:

QUESTION: 4

Prussian blue is formed when [1989]

Solution:

Potassium ferrocyanide solution is added to Fe3+ ions in solution to give deep blue solution or precipitate.

QUESTION: 5

Photographic films and plates have an essential ingredient of [1989]

Solution:

AgBr is highly photosensitive and is used in photographic films and plates.

QUESTION: 6

Nitriding is the process of surface hardening of steel by treating it in an atmosphere of [1989]

Solution:

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.

QUESTION: 7

While extracting an element form its ore, the ore is ground and leached with dil. potassium cyanide solution to form the soluble product potassium argento cyanide. The element is [1989]

Solution:

Cyanide process is used in the metallurgy of Ag

QUESTION: 8

The electronic configurations of four elements are given below. Which element does not belong to the same family as others ? [1989]

Solution:

[ Ne]3s23p 5 is the electronic configuration of a p-block element whereas other configuration are those of d-block elements

QUESTION: 9

The composition of ‘golden spangles’ is [1990]

Solution:

PbI2 is yellow and is called golden spangles.

QUESTION: 10

A blue colouration is not obtained when [1989]

Solution:

QUESTION: 11

The electronic configuration of Cu (atomic number 29) is [1991]

Solution:

Electronic configuration of Cu(29) is 1s2 2s2 2p6 3p2 3p6 4s1 3d10 and not 1s2, 2s2 2p6 3s2 3p6 4s2, 3d9 due to extra stability of fully filled orbitals.

QUESTION: 12

Cinnabar is an ore of [1991]

Solution:

Cinnabar (HgS) is an ore of Hg.

QUESTION: 13

The transition elements have a general electronic configuration [1991]

Solution:

General electronic configuration of transition elements is (n - 1)d1 -10ns1- 2

QUESTION: 14

When CuSO4 is electrolysed using platinum electrodes, [1993]

Solution:

At cathode :  

At anode : 

QUESTION: 15

The most durable metal plating on iron to protect against corrosion is [1994]

Solution:

Galvanisation is the process of deposition of zinc metal on the surface of Fe to prevent it from rusting etc. Zinc forms a protective layer of basic carbonate (ZnCO3. Zn(OH)2) on it.

QUESTION: 16

The common oxidation states of Ti are [1994]

Solution:

The minimum oxidation state in transition metal is equal to the number of electrons in 4s shell and the maximum oxidation state is equal to the sum of the 4s and 3d electrons.
Ti  3d2 4s2 hence minimum oxidation state is +2 and maximum oxidation state is +4. Thus the common oxidation states of Ti are +2, +3 & +4

QUESTION: 17

When (NH4)2 Cr2O7 is heated, the gas evolved is[1994]

Solution:

QUESTION: 18

Actinides [1994]

Solution:

Actinides have variable valency due to very small difference in energies of 5f, 6d and 7s orbitals. Actinides are the elements from atomic number 89 to 103.

QUESTION: 19

Among the lanthanides the one obtained by synthetic method is [1994]

Solution:

Pm is obtained by synthetic method.

QUESTION: 20

Stainless steel contains iron and [1995]

Solution:

Stainless steel contains 73% Fe, 18% Cr and 8% Ni.

QUESTION: 21

Cuprous compounds such as CuCl, CuCN and CuSCN are the only salts stable in water due to

Solution:

The smaller is the size of cation, the more is heat of  hydration. Since hydration is exothermic process, thus heat evolves and hence system having lower energy are stable.

QUESTION: 22

K2Cr2O7 on heating with aqueous NaOH gives [1997]

Solution:

Hence ion is obtained.

QUESTION: 23

The lanthanide contraction is responsible for the fact that [1997]           (Atomic numbers : Zr = 40, Y = 39, Nb = 41, Hf = 72, Zn = 30)

Solution:

We know that regular decrease in the size of the atoms and ions is called lanthanide contraction. In vertical column of transition elements there is a very small change in size and some times size is found same from second member to third member.The similarity in size of the atoms of Zr and Hf is evident due to the object of lanthanide contraction. Therefore Zr and Hf both have same radius 160 pm.

QUESTION: 24

CrO3 dissolves in aqueous NaOH to give [1997]

Solution:

QUESTION: 25

The electroniccon figuration of gadolinium (Atomic number 64) is [1997]

Solution:

We know that atomic number of gadolinium is 64. Therefore the electronic configuration of gadolinium is [Xe] 4f7 5d1 6s2. Because the half filled and fully filled orbitals are more stable.

QUESTION: 26

Which one of the following elements constitutes a major impurity in pig iron ? [1998]

Solution:

Pig iron is the most impure form of iron and contain highest proportion of carbon (2.5 – 4%).

QUESTION: 27

Which one of the following elements shows maximum number of different oxidation states in its compounds? [1998]

Solution:

We know that lanthanides Eu, La, Gd shows +2, +3, +3 and +3 oxidation states respectively only. while actinides, Am shows +2, +3, +4, +5 and +6 oxidation state. Therefore American (Am) has maximum number of oxidation state.

QUESTION: 28

Which one of the following ionic species will impart colour to an aqueous solution? [1998]

Solution:

We know that chromium (III) salts dissolve in water to give violet solution. The violet colour is due to the hydrated chromium (III) in 

QUESTION: 29

On heating chromite (FeCr2O4) with Na2CO3 in air, which of the following product is obtained? [1999]

Solution:

By heating chromite with Na2 CO3, Na2CrO4 is obtained

QUESTION: 30

The addition of excess of aqueous HNO3 to a solution containing [Cu(NH3)4]2+ produces [1999]

Solution:

[Cu (NH3)4]2+ on addition of excess of aqneous HNO3 gives [Cu (H2O)4]2+

QUESTION: 31

An acidic solution of 'X' does not give precipitate on passing H2S through it. 'X' gives white precipitate when NH4OH is added to it. The white precipitate dissolves in excess of NaOH solution.Pure 'X' fumes in air and dense white fumes are obtained when a glass rod dipped in NH4OH is put in the fumes. Compound 'X' can be [1999]

Solution:

Given reactions (white precipitate with H2S in presence of NH4OH) indicate that 'X' should be ZnCl2 which explains all given reactions

QUESTION: 32

Of the following transition metals, the maximum numbers of oxidation states are exhibited by: [2000]

Solution:

Manganese shows max. no. of oxidation states, +2, +3, + 4, + 5, + 6, + 7
Other metals shows the following oxidation states
Cr = + 2, +3, + 4, + 5, + 6
Fe = + 2, + 3
Ti = + 2, + 3, + 4

QUESTION: 33

Which of the following forms colourless compound? [2000]

Solution:

Scandium ion doesn’t contain any unpaired electron in d orbitals hence it form colourless compound.

QUESTION: 34

German silver is an alloy of [2000]

Solution:

German Silver Composition : Cu = 56%, Zn = 24%, Ni = 20%

QUESTION: 35

Which of the following combines with Fe (II) ions to form a brown complex? [2000]

Solution:

We know that when nitrogen oxide (NO) combines with Fe (II) ions, a brown complex is formed. This reaction is called brown ring test