d and f Block Elements — Page 15 | JEE Chemistry

Q141

In the following reactions, ZnO is respectively acting as a/an : (a) ZnO + Na2O

\to

Na2ZnO2 (b) ZnO + CO2

\to

ZnCO3

A base and base

B acid and acid

C acid and base

D base and acid

Correct Answer

Option C

Solution

Zinc oxide (ZnO) when react with Na2O it act as acid while with CO2 it act as base.

Therefore, it is an amphoteric oxide. (a) ZnO + Na2O $\to$ Na2ZnO2 Acid Base Salt (b) ZnO + CO2 $\to$ ZnCO3 Base Acid Salt

Q142

Match with : (Both having metallurgical terms) .tg .tg

List - I		List - II
(a)	Concentration of Ag ore	(i)	Reverberatory furnace
(b)	Blast furnace	(ii)	Pig iron
(c)	Blister copper	(iii)	Leaching with dilute NaCN solution
(d)	Froth floatation method	(iv)	Sulfide ores

A (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)

B (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)

C (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)

D (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

Correct Answer

Option A

Solution

(a) Concentration of Ag is performed by leaching with dilute NaCN solution (b) Pig iron is formed in blast furnace (c) Blister Cu is produced in Bessemer converter (d) Froth floatation method is used for sulphide ores.

Note : During extraction of Cu reverberatory furnace is involved.

Q143

The electronic configuration of Pt (atomic number 78) is :

A [Xe] 4f14 5d9 6s1

B [Kr] 4f14 5d10

C [Xe] 4f14 5d10

D [Xe] 4f14 5d8 6s2

Correct Answer

Option A

Solution

Atomic number of Pt is 78 Electronic configuration is – 78Pt $\to$ [Xe] 4 f14 5d9 6s1 (Exceptional electronic configuration)

Q144

The elements with atomic numbers 101 and 104 belong to, respectively :

A Group 6 and Actinoids

B Actinoids and Group 4

C Group 11 and Group 4

D Actinoids and Group 6

Correct Answer

Option B

Solution

Actinoids contains 14 elements with atomic number 90 to 103.

Hence element with atomic number 101 is Actinoids.

Element with atomic number 104 is a d-block element of group 4.

Q145

Which of the following ions has the maximum magnetic moment?

A Mn2+

B Fe2+

C Ti2+

D Cr2+

Correct Answer

Option A

Solution

M{n^{ + + }} - 5\,\,

unpaired electrons

F{e^{ + + }} - 4\,\,

unpaired electrons

T{i^{ + + }}

- 2\,\,

unpaired electrons

C{r^{ + + }} - 4\,\,

unpaired electrons hence maximum no. of unpaired electron is present in

M{n^{ + + }}.

NOTE : Magnetic moment $\propto$ number of unpaired electrons

Q146

In the structure of the dichromate ion, there is a :

A linear symmetrical Cr-O-Cr bond.

B non-linear symmetrical Cr-O-Cr bond.

C linear unsymmetrical Cr-O-Cr bond.

D non-linear unsymmetrical Cr-O-Cr bond.

Correct Answer

Option B

Solution

Dichromate ion contain non-linear symmetrical Cr-O-Cr bond.

Q147

For making good quality mirrors, plates of float glass are used. These are obtained by floating molten glass over a liquid metal which does not solidify before glass. The metal used can be :

A tin

B sodium

C magnesium

D mercury

Correct Answer

Option D

Solution

It is mercury because it exists as liquid at room temperature.

Q148

The oxidation state of chromium in the final product formed the reaction between

K{\rm I}

and acidified potassium dichromate solution is :

A

+3

B

+2

C

+6

D

+4

Correct Answer

Option A

Solution

C{r_2}O_7^{2 - } + 6{{\rm I}^ - } + 14{H^ + }\overset{\,}\longrightarrow 3{{\rm I}_2} + 7{H_2}O + 2C{r^{3 + }}

oxidation state of

Cr

is

3+.

Q149

Which one of the following lanthanides exhibits +2 oxidation state with diamagnetic nature? (Given Z for Nd = 60, Yb = 70, La = 57, Ce = 58)

A Nd

B Yb

C La

D Ce

Correct Answer

Option B

Solution

Yb (70) = 4f14 6s2 Yb+2 = 4f14 6s0 $\because$ All the electrons are paired hence Yb+2 is diamagnetic.

Q150

The Eu2+ ion is a strong reducing agent in spite of its ground state electronic configuration (outermost) : [Atomic number of Eu = 63]

A 4f76s2

B 4f6

C 4f7

D 4f66s2

Correct Answer

Option C

Solution

Eu $\to$ [Xe]4f76s2 Eu2+ $\to$ [Xe]4f7