12 Class Fsc Part 2 Short Questions Online Preparation for Chemistry chapter 2 (S-Block elements)

Question # 1

Alkali and alkaline earth metals are reactive elements of periodic table.Justify it.

Ans 1: Alkali and alkaline earth metals are reactive elements of periodic table because,these elements are most electropositive elements.Alkali metals have only one electron in their valence shell.Ionization energy values of alkali metals are very low.
Ans 2: Alkaline earth metals have two electrons in their valence shell.These also have very low ionization values.So both alkali and alkaline earth metals are reactive.

Question # 2

What happened when (a) Lithium Carbonate is heated (b) Beryllium is treated with sodium Hydroxide.

Ans 1: Chemical reactions:
(a)Lithium Carbonate is heated:Lithium has low electropositive character,thus its carbonate are not so stable and therefore decomposed giving lithium oxide on heating.
Li₂CO_{3---------------->}Li₂O + CO₂
Ans 2: (b) Beryllium is treated with sodium Hydroxide:Beryllium reacts with alkalies to give hydrogen as:
Be + 2NaOH -------------------> Na₂BeoO₂+ H₂

Question # 3

What is the role of Gypsum in Agriculture.

Ans 1: Role of Gypsum in Agriculture: Gypsum is applied to the soil as source of calcium and sulphur. The calcium supplied by gypsum in fertilizer is of importance in crop production in area where soils are subject to extensive leaching. Sulphur compounds had been applied to soils because of their observed beneficial effect on plants,sulphur has an influence on chlorophyll development in plant leaves.Although not a constituent o chlorophyII,plants deficient in sulphur exhibits a pale green color.The root system of several plants have been observed to be greatly enlarged by the application of sulphur containing materials such as gypsum.

Question # 4

How Gypsum is converted into Plaster of Paris?

Ans 1: When gypsum is heated under carefully controlled conditions,It loses three quarters of its water of crystallization,the resulting product is called Plaster of Paris.Calcium sulphate occurs in nature as gypsum CaSO₄.2H₂O.When it is heated above 100^oC,it loses three quarters of its water of crystallization,giving a white powder which is known as Plaster of Paris.
2CaSO₄.2H₂O--------->(CaSO₄)₂.H₂O+3H₂O
Gypsum Plaster of Paris

Question # 5

What happen when beryllium react with sodium hydroxide and lithium hydride reacts with water?

Ans 1: Beryllium reacts with alkalies to give hydrogen as:
Be+2NaOH---------------------->Na₂BeO₂+ H₂
Ans 2: Lithium hydrides are useful sources of hydrogen when treated with water:
LiH +H₂O------------------->LiOH +H₂

Question # 6

Lithium is least reactive element of all alkali metals.

Ans 1: Lithium is least reactive element of all alkali metals because of its small radius and high charge density.The nuclear charge of Li⁺ion is screened only by a shell of two electrons.The so called anomalous properties of lithium are due to the fact that lithium is unexpectedly far less electropositive than other alkali metals.

Question # 7

Why is CaCl₂added in molten Nacl in Down's cell?

Ans 1: CaCl₂added in molten NaCl in Down's cell: Sodium chloride is used as raw material in Down's cell.The melting point of sodium chloride is 801^oC. Some calcium chloride is added to lower the melting point of sodium chloride.Calcium chloride permits the furnace to operate at about 600^oC.

Question # 8

Give advantages of Down's cell.

Ans 1: i) Metallic fog is not produced.
ii) Liquid sodium can easily be collected at 600^oC.
iii) Material of cell is not attacked by the products formed during the electrolysis.

Question # 9

When sodium reacts with water,hydrogen which evolves catches fire,Why?

Ans 1: A small piece of sodium floated on water reacts vigorously to liberate hydrogen and produce metal hydroxide.The reaction is highly exothermic.The energy produced by the reaction may even ignite the hydrogen.
2Na + 2H₂O----------->2NaOH+H₂

Question # 10

Give reactions of BeO with a) NaOH b) H₂SO₄.

Ans 1: a) Reactions of BeO with NaOH:BeO + 2NaOH------>Na₂BeO₂+ H₂O
b) Reactions of BeO with H₂SO₄:BeO + H₂SO₄--------->BeSO₄+ H₂O

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12 Class Fsc Part 2 Short Questions Online Preparation for Chemistry chapter wise

Online Short Questions For Chapter 2 "12th Class Chemistry Chapter 2 Short Questions Preparation "

Chemistry - 12th Class Chemistry Chapter 2 Short Questions Preparation

Alkali and alkaline earth metals are reactive elements of periodic table.Justify it.

What happened when (a) Lithium Carbonate is heated (b) Beryllium is treated with sodium Hydroxide.

What is the role of Gypsum in Agriculture.

How Gypsum is converted into Plaster of Paris?

What happen when beryllium react with sodium hydroxide and lithium hydride reacts with water?

Lithium is least reactive element of all alkali metals.

Why is CaCl2added in molten Nacl in Down's cell?

Give advantages of Down's cell.

When sodium reacts with water,hydrogen which evolves catches fire,Why?

Give reactions of BeO with a) NaOH b) H2SO4.

Prepare Complete Set Wise Questions For Chapter 2 "12th Class Chemistry Chapter 2 Short Questions Preparation "

Set 1

Set 2

Set 3

Set 4

12th Class Chemistry Chapter 2 Short Questions Preparation - Set 1

Alkali and alkaline earth metals are reactive elements of periodic table.Justify it.

What happened when (a) Lithium Carbonate is heated (b) Beryllium is treated with sodium Hydroxide.

What is the role of Gypsum in Agriculture.

How Gypsum is converted into Plaster of Paris?

What happen when beryllium react with sodium hydroxide and lithium hydride reacts with water?

Lithium is least reactive element of all alkali metals.

Why is CaCl2added in molten Nacl in Down's cell?

Give advantages of Down's cell.

When sodium reacts with water,hydrogen which evolves catches fire,Why?

Give reactions of BeO with a) NaOH b) H2SO4.

12th Class Chemistry Chapter 2 Short Questions Preparation - Set 2

What are main uses of Plaster of Paris?

Write Chemical Formulae of (a) Carnallite (b) Borax.

What is mil;k of Magnesia and for which treatment it used.

Give two uses of Lime in industry.

What happens when: 1) Li2CO3 2) Na2CO3is heated.

Why group II-A elements are called Alkaline Earth Metals.

How chlorine produced in Diaphragm cell,is protected to react with Hydroxide ions?

Mention two major problems that may arise in Nelson's cell.

2% gypsum is added in the cement.Justify.

Lithium is least reactive element of all alkali metals.

12th Class Chemistry Chapter 2 Short Questions Preparation - Set 3

How Plaster of Paris is formed.Give its two uses?

Give advantages of Down's cell.

How potassium superoxide KO2has very interesting use in breathing equipment for mountains and space crafts?

Write points to show peculiar behavior of Berylium.

Give the name and formula for common minerals of Be.

What happened when (a) Lithium Carbonate is heated (b) Beryllium is treated with sodium Hydroxide.

Write a brief note on the occurrence of alkaline earth metals?

Why S-block elements are called as alkali metals and alkaline earth metals?

Mention two major problems that may arise in Nelson's cell.

What is the role of Gypsum in Agriculture.

12th Class Chemistry Chapter 2 Short Questions Preparation - Set 4

Which Elements are called as alkaline earth metals?Why this name is used for these elements?

What is cement plaster and Hard finish plaster?

What is mil;k of Magnesia and for which treatment it used.

Give two uses of Lime in industry.

Why group II-A elements are called Alkaline Earth Metals.

What happened when (a) Lithium Carbonate is heated (b) Beryllium is treated with sodium Hydroxide.

Write the advantages of Nelson's cell.

What is the role of Gypsum in Agriculture.

Alkali and alkaline earth metals are reactive elements of periodic table.Justify it.

Why lime water turns milky CO2but becomes clear with excess CO2?

12th Class Chemistry Chapter 2 Preparation

Share your comments & questions here

Why is CaCl₂added in molten Nacl in Down's cell?

Give reactions of BeO with a) NaOH b) H₂SO₄.

Why is CaCl₂added in molten Nacl in Down's cell?

Give reactions of BeO with a) NaOH b) H₂SO₄.

What happens when: 1) Li₂CO₃ 2) Na₂CO₃is heated.

How potassium superoxide KO₂has very interesting use in breathing equipment for mountains and space crafts?

Why lime water turns milky CO₂but becomes clear with excess CO₂?