F Block

Question 1

How many stable oxidation states do lanthanoids have ?

Answer 1

Only 1.

Question 2

Why is the chemistry of actinkids complicated ?

Answer 2

1. Wide range of oxidation states.
2. Radioactivity

Question 3

The most stable O.S of lanthanoids are

Answer 3

+ 3

Question 4

Electronic configuration of lanthanoids

Answer 4

6s² 4f ( 1 - 14)

Question 5

Lanthanoid contraction causes

Answer 5

Radii of 3rd series to be similar to the 2nd series.

Question 6

Which elements are termed as lanthanoids ?

Answer 6

14 elements in the 6th period
( Z = 58 - 71)

Question 7

Standard electrode value for Ce⁴/Ce³ is

Answer 7

+ 1.74 V

Question 8

Behaviour of Samarium (Sm) is similar to the element ?

Answer 8

Europium ( Eu)

Question 9

Oxidation states that Samarium exhibits

Answer 9

+2 and +3

Question 10

Terbium with + 4 O.S has properties

Answer 10

1. Oxidant
2. Half filled f orbital

Question 11

Ytterbium (Yb) with +2 O.S properties.

Answer 11

1. f¹⁴ configuration
2. Reductant

Question 12

How is Eu ² ion formed ?

Answer 12

1. Losing two s- electrons
2. f ⁷ configuration

Question 13

Property of Europium in +2 oxidation state.

Answer 13

Strong reducing agent.

Question 14

Which elements can exhibit +4 oxidation states only in oxides MO²

Answer 14

1. Praseodymium(Pr)
2. Neodymium ( Nd)
3. Terbium (Tb)
4. Dysprosium (Dy)

Question 15

Hardness of lanthanoid series

Answer 15

Hardness increases with atomic number.

Question 16

Which element in the lanthanoid series is steel hard ?

Answer 16

Samarium.

Question 17

lanthanoid elements on exposure to air .

Answer 17

Tarnish rapidly.

Question 18

Physical property lanthanoids

Answer 18

1.Silvery white
2. soft metals.
3. Metallic structure
4. Good conductors

Question 19

Range of melting points of lanthanoid elements .

Answer 19

1.1000 to 1200 K
2. Samarium - 1623 K

Question 20

What affects the colours of the lanthanoid ions ?

Answer 20

Presence of f electrons

Question 21

Whoch of the lanthanoid ions do not show any colour ?

Answer 21

1.Lanthanum - La³
2.Lutetium - Lu ³

Question 22

Why are the absorption bands narrow in the lanthanoid series ?

Answer 22

Excitation within f levels.

Question 23

Magnetic properties of lanthanoid ions.

Answer 23

All lanthanoid ions are paramagnetic.
Except f⁰ and f¹⁴

Question 24

Which lanthanoid ions are NOT paramagnetic?

Answer 24

1. f⁰ - La³ and Ce⁴
2. f¹⁴ - Yb² and Lu³

Question 25

Ionisation entalpies of lanthanoids

Answer 25

A) I.E.1. 600 kJ /mol B) I.E.2. 1200 kJ /mol

Question 26

Reactive behaviour of lanthanoid series is similar to the element ?

Answer 26

initially- calcium Further - aluminium

Question 27

Properties of hydroxides of lanthanoids.

Answer 27

1. M(OH)³ 2. Definite Compounds 3. Basic in nature (like group 2 oxides)

Question 28

The best single use of lanthanoids

Answer 28

Production of alloy steels for plates and pipes.

Question 29

Well known alloy of lanthanoid

Answer 29

Mishmetall- 95% Ln and 5% iron

Question 30

Mishmetall is used in ?

Answer 30

Mg based alloys to produce bullets, shell and lighter flint.

Question 31

Mixed Oxides of lanthanoids are used for

Answer 31

Catalysts in petroleum cracking

Question 32

Individual oxides of lanthanoids are used as

Answer 32

Phosphors in television screens and flourescing surfaces.

Question 33

Ln with halogens form

Answer 33

LnX³

Question 34

Ln when heated with Sulphur gives

Answer 34

Ln² S³

Question 35

When Ln burns in O²

Answer 35

Ln ²O³

Question 36

Cerium (Ce) in +4 oxidation state is a

Answer 36

Strong oxidant.

Question 37

As ionic radius decreases from Praseodymium (Pr) to Lutetium (Lu) ?

Answer 37

Basicity decreases as well.

Question 38

Whoch elements have almost the same radii due to lanthanoid contraction ?

Answer 38

Zirconium (Zr) and Hafnium (Hf)

Question 39

Reason of lanthanoid contraction is

Answer 39

Negligible screening effect of f orbitals.

Question 40

Why do actinoids have more more number of oxidation states

Answer 40

Less energy difference between 5f and 6d orbitals than than between 4f and 5d. Hence , 5f , 6d and 7s levels have comparable energies.

Question 41

General oxidation state of actinoids.

Answer 41

+3

Question 42

Which elements shows only +4 O.S in actinoids ?

Answer 42

Thorium (Th)

Question 43

Which elements of actinoids exhibit +7 oxidation state?

Answer 43

Neptunium (Np) Plutonium (Pu)

Question 44

Which ions of actinoids tend to hydrolyse?

Answer 44

+3 and +4 ions

Question 45

Which elements of actinoids exhibit only +3 oxidation state?

Answer 45

Ac, Cf - Lr. Actinium, Californium to lawrencium

Question 46

The actinoid contraction is caused by

Answer 46

Poor shielding of 5f electrons

Question 47

Half life of lawrencium (Lr)

Answer 47

3 minutes

Question 48

Ionisation enthalpies of actinoids series

Answer 48

Not accurately known but lower than that of lanthanoids.

Question 49

Which compound from transition metals is manufactured for the pigment industry ?

Answer 49

TiO

Question 50

Transition elements that the Battery industry requires

Answer 50

MnO² compound Zinc, Nickel / Cadmium

Question 51

Elements of which group are termed as coinage metals .?

Answer 51

Group 11

Question 52

The silver UK coins are alloys of

Answer 52

Copper (Cu) and Nickel (Ni)

Question 53

The compound V²O⁵ is used for

Answer 53

Catalyst for oxidation of SO² in manufacture of sulphuric acid

Question 54

Zeigler catalyst is made of and used for

Answer 54

Made of TiCl⁴ and Al( CH³) ³ Used for manufacture of polyethylene ( polythene)

Question 55

Nickel catalysts are used for

Answer 55

Hydrogenation of fats

Question 56

What is the Wacker process

Answer 56

Oxidation of ethyne to ethanal, catalysed by PdCl²

Question 57

The photographer industries rely on light sensitive properties of

Answer 57

AgBr - Silver bromide.

Question 58

What catalyst is used for the Haber process

Answer 58

Iron catalyst

Question 59

What helps in polymerisation of alkyne?

Answer 59

Nickel complexes.