s block

Question 1

MP trend in s block

Answer 1

grp 1: MP decreases down grp regularly
grp 2 : Mg has lowest MP for rest it decreases down regularly

Question 2

BP trend in s block

Answer 2

grp 1: BP decreases down grp regularly
grp 2: BP decreases till Sr then increases.
Mg has lowest BP.
(due to weak cohesive force)

Question 3

Density trend in s block

Answer 3

Density increases down the group(K has exceptionally low density, due to large at. vol)
[Li<K<Na<Rb<Cs]
grp 2:Density decreases till Ca then increases.
[Ca<Mg<Be<Sr<Ba]

Question 4

Relation between hydration energy and reducing character

Answer 4

Higher the hydration energy better is the reducing character.

Question 5

Which is the best RA in the group?

Answer 5

Li has highest hydration energy in all of periodic table (best RA in all of periodic table

Question 6

Li

Answer 6

carmine yellow

Question 7

Na

Answer 7

golden yellow

Question 8

L

Answer 8

voilet (lilac)

Question 9

Ba

Answer 9

apple green

Question 10

Ca

Answer 10

brick red

Question 11

Sr

Answer 11

crimson red

Question 12

Rb

Answer 12

ruby violet

Question 13

Cs

Answer 13

blue

Question 14

oxide formation

Answer 14

Li forms monoxides and Na forms peroxide. rest metals forms superoxide.
tendency to form superoxide increases down the group since larger cation balances larger anion.

Question 15

solubility of alkali halides

Answer 15

Li is less soluble doe to high lattice energy.
rest halides are solube in organic solvent

Question 16

heating effect (IMP)

Answer 16

Be and Mg undergo hydrolysis on heating whereas other metals undergo dehydration

Question 17

Carbonates

Answer 17

grp 1: except Li all other metals forms thermally stable carbonates
grp 2: insoluble carbonates, solubility decreases down the group.
BeCO3 is unstable can only be stored in atmosphere of oxygen

Question 18

bicarbonates existence in solid state

Answer 18

Li bicarbonate doesnt exist in solid state .
NaHCO3- polymer
KHCO3- dimer

Question 19

nitrates on heating

Answer 19

grp 1: except Li all form MNO2 and O2. Li forms Li2O, NO2, O2

Question 20

soln in liq. ammonia

Answer 20

both form deep blue solution. colour id due to solvated ammonium electrons

Question 21

lepidolite

Answer 21

Li2Al2(SiO3)3(FOH)2

Question 22

borax

Answer 22

Na2B4O7.10H2O

Question 23

saltpetre

Answer 23

NaNO3

Question 24

sylvinite

Answer 24

NaCl

Question 25

Sylvite

Answer 25

KCl

Question 26

carnalite

Answer 26

KCl.MgCl2.6H2O

Question 27

Li uses

Answer 27

1) Li stearate used in automobile grease
2) Li2CO3 is added in bauxite in electrolytic production of AL as it lowers mp
3) to toughen glass
4) used for making electrochemical cells

Question 28

Na uses

Answer 28

1) Caustic soda NaOH (imp alkali) used for making organic and inorganic compounds, paper making
2) Soda ash Na2CO3 soap making
3) NaHCO3 is used in baking powder

Question 29

K uses

Answer 29

1) fertilizers
2)KNO3 explosive
3) KMnO4 used in manufacture os sacchrine and as OA
4) K2CO3 ceramics, colour tv
5) KO2 used in breathing apparatus in submarines
6) KBr used in photography

Question 30

miscibilty of Li

Answer 30

due to small size lithium is miscible with an above 380 but is immiscible with others. others are miscible with each other in all propotions