IIT JEE -2013 CHEMISTRY "CARBON FAMILY"

P. JOY

IIT-JEE

INORGANIC

CHEMISTRY

CARBON FAMILY

Note

EXERCISE # 3 ELEMENTAL CARBON : Q.1

Why 'C' shows highest properties of catenation ?

Q.2

Which allotrope of carbon is thermodynamically more stable ?

Q.3

Why graphite is good conductor of electricity ?

Q.4

Which is thermodynamically most stable ? Graphite, Diamond or fullerene.

Q.5

Which element occurs in both very hard and very soft form ?

Q.6

Which allotrope of carbon is insoluble in solvent ?

Q.7

How fullerene was originally prepared ?

Q.8

Can fullerene be prepared by evaporation of graphite by electric arc ?

Q.9

How many 'C' atoms are there normally in fullerene ?

Q.10

What is the colour of C60 in toluene ?

Q.11

What is the colour of C70 in Toluene ?

Q.12

What is the shape of C60 ?

SILICON, TIN LEAD : Q.13

In which form does silicon show its allotropy ?

Q.14

What is the purest form of silicon ?

Q.15

Which allotrope of Si is isomorphous with carbon ?

Q.16

What are corundum and carborundum ?

Q.17

How many allotropes of Sn exist ?

Q.18

What are three crystalline modifications of tin ?

Q.19

How various allotropes of tin are related to temperature ?

Q.20

What is tin disease, tin pest or tin plague ?

Q.21

What is tin cry ?

Q.22

How tin is purified ?

GROUP IV OXIDES : Q.23

Which of two has a dipole moment CO & CO2 ?

Q.24

What are the oxides of carbon ?

Q.25

Which acid anhydride is CO2 ?

Q.26

Which acid anhydride is CO ?

Q.27

Which acid anhydride is carbon sesquioxide C3O2 ?

Q.28

Which oxide of IV group is not solid ?

66

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Q.29

Which monoxide of IV group does not exist at toom temperature ?

Q.30

Which monoxide of IV group is neutral ?

Q.31

What is the nature of IV group monoxides ?

Q.32

Which IV group oxides are network solids ?

Q.33

Why CO2 is molecule but SiO2 is 3D network solid ?

Q.34

What are the nature of CO2, SiO2, GeO2, SnO2, PbO2 ?

Q.35

Which dioxide of nonmetal C, S, N or Cl does not act as reducing agent?

Q.36

What is the hybridisation state of Si in SiO2 ?

Q.37

Why CO2 is a gas while SiO2 is a solid ?

Q.38

Which oxide of tin (SnO, SnO2) is/are amphoteric ?

Q.39

Why heating of SnC2O4 does yield SnO instead of SnO2 ?

Q.40

What happens when SnO2 is reacted with (i) H2SO4 (ii) NaOH

Q.41

What are various oxides of Pb ?

Q.42

Which lead oxide is less stable ?

Q.43

Which oxide of Sn act as a good reducing agent ?

Q.44

What is the nature of π bond in CO2 ?

Q.45

Which of the 2 oxides of lead (PbO, PbO2) is more basic ?

Q.46

Write the preparation of carbon mono-oxide ?

Q.47

What happens when bicarbonates are reacted with mineral acids like dil. HCl ?

Q.48

What happens when metal carbonates are with mineral acids like dil. HCl ?

Q.49

Arrange following in order of stability ? H2CO3, NaHCO3 and Na2CO3

Q.50

Arrange following in order of stability ? NaHCO3, KHCO3 and CsHCO3

Q.51

Arrange following in order of stability H2CO3, Na2CO3, Cs2CO3

Q.52

Why ZnCO3 and MgCO3 on heating decompose into CO2 but not Na2CO3.

Q.53

Write the properties of carbon monoxide :

Q.54

What happens when CO is reacted with following : (i) Oxygen (ii) Sulphur (iii) Chlorine (iv) Fe2O3 (v) FeO (vi) I2O5 (vii) Nickel

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P. JOY Note

67

P. JOY

IIT-JEE

INORGANIC

CHEMISTRY

Note

Q.55

Suggest a chemical test to identify carbondioxide gas.

Q.56

What is the formula of lime stonae, slacked lime, quick lime ?

Q.57

What is the colour of lime water ?

Q.58

What happens when CO2 is passed into water.

Q.59

What happens to solubility when partial pressure of CO2 is increased?

Q.60

When CO2 is passed in water what are the species observed in solution resulted ?

Q.61

What are the different sources of H+ ions in carbonic acid solution ?

Q.62

CO2 is a gas, while SiO2 is a solid, although both carbon and silicon belong to same group.

Q.63

What is drinkold ?

Q.64

Why CO2 cannot be used to entinguish fire caused by magnesium.

Q.65

If it possible to get H2CO3 in solid state.

Q.66

What happens when CaC2 (Calcium carbide) is reacted with water ?

Q.67

Which is thermodynamically more stable (COOH)2 or (SiOOH)2 ?

Q.68

Which form of carbon is thermodynamically more stable ?

Q.69

Which form of carbon is harder diamond / graphite ?

Q.70

If diamond is thermodynamically less stable than graphite. Why cannot graphite be artificially converted into diamond ?

Q.71

Show formation of urea when ammonia is reacted with CO2 at high pressure ?

Q.72

What type of oxides are formed by fourth group elements ?

Q.73

What is the Pb2O3 ?

Q.74

Which oxidation state for fourth group oxide results into more stable form on moving top to bottom ?

Q.75

Which dioxide of group IV is in gaseous state ?

Q.76

Write the similarities and differences between CO & CO2 ?

Q.77

Write the reaction of CO2 with NaOH

Q.78

Write the lime water test of CO2 ?

Q.79

What happens when CO is added to water ?

Q.80

What happens when CO passed in NaOH at high pressure ?

Q.81

What happens if SiO2 is added to water ?

Q.82

SiO2 reacts with CaO then what is product, where this reaction is mainly applied. What is the Basic of reaction.

68

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GROUP IV HALIDES : Q.83

What happens when SnCl2.2H2O crystals are heated ?

Q.84

Which of the two SnCl2 or SnCl4 is a liq. at room temperature ?

Q.85

What is butter of Sn ? What is its major use.

Q.86

What are the addition compounds of SnCl2 & NH3 ?

Q.87

What is the double salt of SnCl4 with NH3 ?

Q.88

How calomel is produced by SnCl2 ?

Q.89

Which tin compound is used in tooth paste to help tooth decay ?

Q.90

Which property of tin makes it useful for tinning of utensils ?

Q.91

What happens when AuCl3 is treated with SnCl2 ?

Q.92

How PURPLE OF CASIUS is formed ?

Q.93

What happens when butter of tin is hydrolysed with excess of water?

Q.94

What happens when tin metal is reacted with conc. HNO3 ?

Q.95

Which tin halide out of SnCl4, SnBr4, SnI4 is coloured ?

Q.96

How Tin (II) fluoride is obtained ?

Q.97

Why Pb715 has higher I.E. than Sn707 ?

Q.98

Why do PbCl4 acts as strong oxidising agent ?

Q.99

SiF62– exist but not CF62– explain why ?

Q.100

Why PbCl2 is ionic where is PbCl4 is covalent.

P. JOY Note

SILICONS : Q.101

What are silicones and what are its different units.

Q.102

Why two hydroxy groups on silicon atom is stable although 2-OH groups are unstable on C atom ?

Q.103

What is the general formula of organosilicone ?

Q.104

What are the group you can use in place of methyl group to produce silicone.

Q.105

How the name silicone is derived for the polymer R2SiO ?

Q.106

What happens when SiCl4 is reacted with following (A) 1 mole of CH3MgCl (B) 2 mole of CH3MgCl (C) 3 mole of CH3MgCl (D) 4 mol of CH3MgCl

Q.107

What happens when SiCl4 subjected to strong heating ?

Q.108

What happens when dialkyldichloro silanes or diaryl dichlorosilanes are subjected to hydrolysis & then heated strongly ?

Q.109

What are silanes and germanes ? What are their general formula.

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Note

Q.110

How silanes are different than alkanes ?

Q.111

What happens when mixture of silane and H2 is bubbled through water ?

Q.112

What is silica Garden ?

Q.113

Why trimethyl amine is pyramidal but trisilyl amine is planar ?

Q.114

Which of two is more basic N(CH3)3 or N(SiH3)3 ?

SILICATES : Q.115

What is the hybridisation state of Si in SiO2 ?

Q.116

What happens when SiO2 is reacted (heated) with alkalis and alkali metal carbonates ?

Q.117

KNO3 on heating produce KNO2 and O2 but what happens when KNO3 is heated with SiO2 ?

Q.118

What happens when SiO2 is reacted with following ? (a) KOH (b) CaCO3 (c) KNO3 (d) HF (e) Coke

Q.119

What happens when Si is fused with NaOH in air ?

Q.120

What is the definition of glass ?

Q.121

What type of glass is K2O.PbO.4SiO2 ?

Q.122

What is the formula of soda glass ?

Q.123

What is the formula of water glass

Q.124

What is Crookes glass ? What is its speciality ? Which metal compound is present in it ?

Q.125

What is Na2SiO3. CaSiO3.4SiO2 ?

Q.126

What do you call K2O.CaO.4SiO2 ?

Q.127

Which type of anions are present in pyrex glass ?

Q.128

How borosilicate glass are obtained ?

Q.129

Which type of glass has lane thermal expansion ?

Q.130

Which type of glass are prisms and lenses are made up of ?

Q.131

Name an acid which dissolves silica ?

Q.132

Why HF acid is stored in plastic bottles and not glass bottles ?

Q.133

Which compound is formed when glass reacts with HF ?

Q.134

Which acid is used for etching glass ?

Q.135

What pseudo solids ?

Q.136

What hapend when SiCl4 is subjected to strong heating ?

Q.137

What is the formula of orthosilicate anion ? Why is it important.

70

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ELEMENTAL CARBON : Q.1

Why 'C' shows highest properties of catenation ?

Ans.

The strength of C–C bond is very high.

Q.2

Which allotrope of carbon is thermodynamically more stable ?

Ans.

Graphite

Q.3

Why graphite is good conductor of electricity ?

Ans.

Free electrons present in 2p orbitals of graphite

Q.4

Which is thermodynamically most stable ? Graphite, Diamond or fullerene.

Ans.

Graphite

Q.5

Which element occurs in both very hard and very soft form ?

Ans.

C

Q.6

Which allotrope of carbon is insoluble in solvent ?

Ans.

Diamond

Q.7

How fullerene was originally prepared ?

Ans.

Fullerenes are produced by evoparation of graphite by lesser.

Q.8

Can fullerene be prepared by evaporation of graphite by electric arc ?

Ans.

Yes

Q.9

How many 'C' atoms are there normally in fullerene ?

Ans.

60

Q.10

What is the colour of C60 in toluene ?

Ans.

Purple colour

Q.11

What is the colour of C70 in Toluene ?

Ans.

Red orange colour

Q.12

What is the shape of C60 ?

Ans.

Socker's ball

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P. JOY Note

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P. JOY

IIT-JEE

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CHEMISTRY

Note

SILICON, TIN LEAD : Q.13

In which form does silicon show its allotropy ?

Ans.

α-Quartz ⇔ β-Quartz ⇔ Tridymite

Q.14 Ans.

What is the purest form of silicon ? β-Quartz

Q.15 Ans.

Which allotrope of Si is isomorphous with carbon ? SiO2

Q.16 Ans.

What are corundum and carborundum ? Corundum (α−Al2O3) and Carborundum (SiC)

Q.17 Ans.

How many allotropes of Sn exist ? Three

Q.18

What are three crystalline modifications of tin ?

Ans.

α-Sn ⇔

Q.19

How various allotropes of tin are related to temperature ?

Ans.

α-Sn ⇔

Q.20 Ans.

What is tin disease, tin pest or tin plague ? The conversion of white tin (β-Sn) is accompainied by an increase in volume and the letter, being very brittle, easily crumbles down to powder, this phenomenon is known as tin disease.

Q.21 Ans.

What is tin cry ? When bent the metal produces a cracking sound due to rubbing of crystals over one another is known as tin cry.

Q.22 Ans.

How tin is purified ? Tin is purifyed by electrolytic method

72

840

15ºC

15ºC

CARBON FAMILY

1600ºC

⇔

cristobalite

160ºC

β-Sn

β-Sn

⇔

Rhombic Sn

160ºC

⇔ Rhombic Sn

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GROUP IV OXIDES : Q.23 Ans.

Which of two has a dipole moment CO & CO2 ? CO

Q.24 Ans.

What are the oxides of carbon ? CO, CO2, C3O2

Q.25 Ans.

Which acid anhydride is CO2 ? H2CO 3

Q.26 Ans.

Which acid anhydride is CO ? HCOOH

Q.27 Ans.

Which acid anhydride is carbon sesquioxide C3O2 ? Malonic acid

Q.28 Ans.

Which oxide of IV group is not solid ? CO2

Q.29 Ans.

Which monoxide of IV group does not exist at toom temperature ? SnO

Q.30 Ans.

Which monoxide of IV group is neutral ? CO

Q.31 Ans.

What is the nature of IV group monoxides ? CO → neutral, others → acidic

Q.32 Ans.

Which IV group oxides are network solids ? SiO2

Q.33 Ans.

Why CO2 is molecule but SiO2 is 3D network solid ? SiO2 does not have tendency of pπ-pπ overlapping.

Q.34 Ans.

What are the nature of CO2, SiO2, GeO2, SnO2, PbO2 ? CO2, SiO2 Acidic;

P. JOY Note

GeO2, SnO2 Amphoteric; PbO2 Basic Q.35 Ans.

Which dioxide of nonmetal C, S, N or Cl does not act as reducing agent? CO2

Q.36 Ans.

What is the hybridisation state of Si in SiO2 ? sp 3

Q.37 Ans.

Why CO2 is a gas while SiO2 is a solid ? SiO2 form

Q.38 Ans.

Which oxide of tin (SnO, SnO2) is/are amphoteric ? Both SnO and SnO2

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P. JOY Q.39 Ans.

IIT-JEE

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CHEMISTRY

CARBON FAMILY

Note

Why heating of SnC2O4 does yield SnO instead of SnO2 ? ∆

SnC2O4   → SnO + CO + CO2

Oxidation of SnO to SnO2 is checked by CO Q.40

What happens when SnO2 is reacted with (i) H2SO4 (ii) NaOH

Ans.

NaOH SnO2   → Na2SnO3 H2SO4 SnO2   → H3SnO3 stannic acid

Q.41 Ans.

What are various oxides of Pb ? PbO, PbO2, Pb2O3, Pb3O 4

Q.42

Which lead oxide is less stable ?

Ans.

PbO 2

Q.43

Which oxide of Sn act as a good reducing agent ?

Ans.

SnO is a good reducing agent between it get oxidised to form SnO2.

Q.44

What is the nature of π bond in CO2 ?

Ans.

Q.45 Ans. Q.46 Ans.

In CO2 pπ - pπ bond is formed as p-orbitals of C & O are of same size thus 2p2p overlapping is formed ? Which of the 2 oxides of lead (PbO, PbO2) is more basic ? PbO Write the preparation of carbon mono-oxide ? (i) From coke High. temp. Coke + Air ¾¾¾¾¾¾ ® CO + N2

(ii) From steam C + H2O → CO + H2

(iii) From HCN/KCN

H 2 SO 4 HCN ¾¾¾¾® CO + H2O + NH H3

2K+CN– + H2SO4 → K2SO4 + 2HCN + CO + H2O

(iv) From K4[Fe(CN)6]

ˆˆˆˆ † K4[Fe(CN)6] + 3H2SO4 ‡ˆˆˆ O4 + FeSO4 + 6HCN ˆ 2K2SO ˆˆˆˆ † HCN + H2SO4 ‡ˆˆˆ H4SO4 ˆ CO + NH Q.47

What happens when bicarbonates are reacted with mineral acids like dil. HCl ?

Ans.

MHCO3 + HCl → MCl + H2O + CO2

Metal bicarbonate dissociates to give corresponding salt, water and carbon dioxide is released. Q.48

What happens when metal carbonates are with mineral acids like dil. HCl ?

Ans.

On reaction of metal carbonates with dil. HCl it give salt and carbonic acid which further break to give CO2 and H2O. MCO3 + 2HCl → 2MCl + H2CO3

H2CO3 → H2O + CO2

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Q.49

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P. JOY Note

Arrange following in order of stability ? H2CO3, NaHCO3 and Na2CO3

Ans.

H2CO3 < NaHCO3 < Na2CO3

Q.50

Arrange following in order of stability ?

Ans. Q.51 Ans. Q.52

NaHCO3, KHCO3 and CsHCO3 NaHCO3 < KHCO3 < CsHCO3 Arrange following in order of stability H2CO3, Na2CO3, Cs2CO3 H2CO3 < Na2CO3 < Cs2CO3 Which of the following on heating produces CO2 : (a) ZnCO3

(b) MgCO3

(c) Na2CO3

Ans.

ZnCO 3, MgCO 3

Q.53

Write the properties of carbon monoxide :

Ans.

(i) It is highly toxic gas. (ii) CO can be combust in CO2

(iii) It is metal carbonyl (ligand) (iv) C ≡ O and N ≡ N are isoelectronic (v) CO and NO are both stable. Q.54

What happens when CO is reacted with following : (i) Oxygen

(ii) Sulphur

(iii) Chlorine

(iv) Fe2O3

(v) FeO

(vi) I2O5

(vii) Nickel Ans.

Reaction with non-metal : CO + S → COS CO + ½O2 → CO2 CO + Cl2 → COCl2

Reaction with metal oxide (reducing agent) : 3CO + Fe 2O3 → 3CO2 + 2Fe CO + FeO → CO2 + Fe

5CO + I2O5 → 5CO2 + I2

Q.55

Suggest a chemical test to identify carbondioxide gas.

Ans.

We use lime water test to identify carbon dioxide. In this test CO2 gas is passed into lime water which results into formation of milky turbidity. On further passage of gas this turbidity disapears. Turbidity is due to calcium carbonate and it dissapears due to formation of bicarbonates.

Q.56

What is the formula of lime stonae, slacked lime, quick lime ?

Ans.

(Solid) CaCO3 : limestone (marble) (ppt) Ca(OH)2 : slacked lime (Solid) CaO : Quick lime

Q.57

What is the colour of lime water ?

Ans.

It is colourless.

Q.58

What happens when CO2 is passed into water.

Ans.

CO2 dissolves and form carbonic acid.

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Q.59

What happens to solubility when partial pressure of CO2 is increased?

Ans.

By Henry's law the mass of dissolved carbondioxide decreases on increasing partial pressure of CO2.

Q.60

When CO2 is passed in water what are the species observed in solution resulted ?

Ans.

Molecular CO2, H2CO3, HCO3–, CO32–, OH–, H+, H2O

Q.61

What are the different sources of H+ ions in carbonic acid solution ?

Ans.

Ka1 of H2CO3, Ka2 of H2CO3 & Kw of H2O

Q.62

CO2 is a gas, while SiO2 is a solid, although both carbon and silicon belong to same group.

Ans.

SiO2 is a three dimensional network solid whereas CO2 exist as descrete molecule in gaseous phase because the pπ-pπ bonding of CO bond is stronger than the pπ-pπ bonding of SiO bond. This silicon prefers to form σ bond instead π bond.

Q.63

What is drikold ?

Ans.

Solid carbondioxide is sold in the name of drikold.

Q.64

Why CO2 cannot be used to entinguish fire caused by magnesium.

Ans.

Fire accidents caused by magnesium cannot be causted by CO2 because magnesium and its compounds react further to produce magnesium carbonate.

CARBON FAMILY

Note

CxHy + O2 → xCO2 + ½H2O 2Mg + O2 → 2MgO MgO + CO2 → MgCO3 Q.65

If it possible to get H2CO3 in solid state.

Ans.

No, CO2 exist in aqueous solution as H2CO3. Thus H2CO3 exist in aqueous form only.

Q.66

What happens when CaC2 (Calcium carbide) is reacted with water ?

Ans.

CaCl2 + H2O → HC ≡ CH + Ca(OH)2

Q.67

Which is thermodynamically more stable (COOH)2 or (SiOOH)2 ?

Ans.

(COOH)2

Q.68

Which form of carbon is thermodynamically more stable ?

Ans.

Graphite

Q.69

Which form of carbon is harder diamond / graphite ?

Ans.

Diamond.

Q.70

If diamond is thermodynamically less stable than graphite. Why cannot graphite be artificially converted into diamond ?

Ans.

Due to high value of activation energy. Through diamond is at higher energy level than graphite at thermodynamically scale but graphite cannot be converted easily into diamond because it high activation energy of the process.

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P. JOY Note

Q.71

Show formation of urea when ammonia is reacted with CO2 at high pressure ?

Ans.

Zwitter ion

Q.72

What type of oxides are formed by fourth group elements ?

Ans.

Fourth group elements forms two types of oxide having general formula of MO and MO2.

Q.73

What is the Pb2O3 ?

Ans.

Pb2O3 is a mixed oxide. Pb2O3 ≡ PbO.PbO2 Fe3O4 ≡ FeO.Fe 2O3

Q.74

Which oxidation state for fourth group oxide results into more stable form on moving top to bottom ?

Ans.

For top elements it is the higher oxidation state and for lower element it is the lower oxidation state.

Q.75

Which dioxide of group IV is in gaseous state ?

Ans.

Except CO2 all oxides are polymeric giant molecule.

Q.76

Write the similarities and differences between CO & CO2 ?

Ans.

Differences between CO & CO2 CO

CO2

1.

C≡O

O=C=O

2.

µ>0

µ=0

3.

Neutral

Acidic

4.

Insoluble in water

Spangly soluble in amphoteric high P → good solute

5.

Highly toxic, 50% is required

Not toxic

for explosion. 6.

Anhydride of HCOOH

Anhydride of H2CO3

7.

CO is isoelectronic to N2(14)

8 + 8 + 6 = 22

8.

CO is ligand

CO2 is not a ligand.

Similarities : 1.

Both are oxides of 'C'

2.

Both are gases.

3.

Both have sp hybridised 'C'

4.

Both have polar C – O bond

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Note Q.77

Write the reaction of CO2 with NaOH

Ans.

CO2 + NaOH → NaHCO3

NaHCO3 + NaOH → Na2CO3 + H2O

Q.78 Ans.

Write the lime water test of CO2 ? Reaction of CO2 with Ca(OH)2 Lime water : Ca(OH)2

Ca2 + 2OH–

Q.79

What happens when CO is added to water ?

Ans.

No reaction.

Q.80

What happens when CO passed in NaOH at high pressure ?

Ans.

It turus into sodium formate.

Q.81

What happens if SiO2 is added to water ?

Ans.

No reaction.

Q.82

SiO2 reacts with CaO then what is product, where this reaction is mainly applied. What is the Basic of reaction.

Ans.

CaSiO3 is formed that is called slag. The reaction is mainly used in glass furnance for extraction of iron. Basis of reaction is acidic oxide reacts to basic oxides. Fe2O3.SiO2 (Hematite)

Fe2O3 + 3CO → 2Fe + 3CO2.

78

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Note

GROUP IV (HALIDES) : Q.83

What happens when SnCl2.2H2O crystals are heated ?

Ans.

SnCl2.2H2O

Q.84

Which of the two SnCl2 or SnCl4 is a liq. at room temperature ?

Ans.

SnCl4

∆

Sn(OH)Cl

Q.85

What is butter of Sn ? What is its major use.

Ans.

SnCl4.5H2O

Q.86

What are the addition compounds of SnCl2 & NH3 ?

Ans.

P. JOY

SnCl2.2NH3

Q.87

What is the double salt of SnCl4 with NH3 ?

Ans.

SnCl4.4NH3

Q.88

How calomel is produced by SnCl2 ?

Ans.

HgCl2 + SnCl2 → Calamel

Q.89

Which tin compound is used in tooth paste to help tooth decay ?

Ans.

SnF2

Q.90

Which property of tin makes it useful for tinning of utensils ?

Ans.

Does not reacts with organic acids.

Q.91

What happens when AuCl3 is treated with SnCl2 ?

Ans.

3SnCl2 + 2AuCl3 → 3SnCl4 + 2Au

Q.92

How PURPLE OF CASIUS is formed ?

Ans.

2 → Sn(OH)4 3SnCl2+ 2AuCl3 → 2Au++ 3SnCl4 

Q.93

What happens when butter of tin is hydrolysed with excess of water ?

Ans.

2 SnCl4.5H2O  → Sn(OH)Cl

HO

HO

Butter of Tin Q.94 Ans.

What happens when tin metal is reacted with conc. HNO3 ? Sn + HNO3 → H3SnO3

Q.95

Which tin halide out of SnCl4, SnBr4, SnI4 is coloured ?

Ans.

SnI4 → yellow, SnCl4 and SnBr4 coloured

Q.96

How Tin (II) fluoride is obtained ?

Ans.

SnO + 2HF → SnF2 + H2O

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P. JOY Q.97

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Why Pb715 has higher I.E. than Sn707 ?

Ans.

Pb has more value of ionization energy then Sn due to poor shielding of the valence shell electrons by the electrons present in d and f subshells.

Q.98

Why do PbCl4 acts as strong oxidising agent ?

Ans.

Because Pb+2 is more stable than Pb+4

Q.99

SiF62– exist but not CF62– explain why ?

Ans.

CARBON FAMILY

Absence of d-orbitals in C

Q.100 Why PbCl2 is ionic where is PbCl4 is covalent. Ans.

80

Fajan's rule

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SILICONS : Q.101 What are silicones and what are its different units. Ans.

Silicons are the polymers and used as a lubricants sheets, resins. SiCl4

CH3MgBr (2mol)

CH3 CH3

Si

CH3

Cl

KOH

Cl

CH3 CH3

CH3

Si

OH

CH3

–H2O

CH3

OH

Si = O

CH3

CH3

HO – Si – OH + HO – Si – OH + HO – Si – OH + HO – Si – OH CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

– O – Si – O – Si – O – Si – O – Si – O– CH3

CH3

– O – Si – O –

CH3

CH3

n

Q.102 Why two hydroxy groups on silicon atom is stable although 2-OH groups are unstable on C atom ? Ans.

Due to pressure of d-orbital in Si an extra π-bond character occur which stabilities it.

Q.103 What is the general formula of organosilicone ? Ans.

(R2SiO)n

Q.104 What are the group you can use in place of methyl group to produce silicone. Ans.

Phenyl group.

Q.105 How the name silicone is derived for the polymer R2SiO ? Ans.

Polymeric organocompounds contain Si–O–Si bonds therefore known as silicones.

Q.106 What happens when SiCl4 is reacted with following (A) 1 mole of CH3MgCl (B) 2 mole of CH3MgCl

(C) 3 mole of CH3MgCl (D) 4 mol of CH3MgCl

1. CH 3MgCl 2. CH 3MgCl

Ans.

SiCl4

3. CH 3MgCl 4. CH 3MgCl

, E D U C A T I O N S

CH3SiCl3 (CH3)2SiCl 2 (CH3)3SiCl3 (CH3)4Si

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Q.107 What happens when SiCl4 subjected to strong heating ? Ans.

CARBON FAMILY

No change

Q.108 What happens when dialkyldichloro silanes or diaryl dichlorosilanes are subjected to hydrolysis & then heated strongly ? Ans.

Silicones are produced.

Q.109 What are silanes and germanes ? What are their general formula. Ans.

Silanes Sin H2n

+ 2

German Gen H2n

+ 2

Q.110 How silanes are different than alkanes ? Ans. Silanes Alkanes Toxic

Not

Autocombust

Not

Reducing agent

Not

Unstable

Stable

Q.111 What happens when mixture of silane and H2 is bubbled through water ? Ans. Vertex of silica is formed. Q.112 What is silica Garden ? Ans. When transition metals are added into soda glass solution. Different type of colour are obtained. Q.113 Why trimethyl amine is pyramidal but trisilyl amine is planar ? Ans. Trimethyl amines sp3, Trisilyl amine sp2 hybridization Q.114 Ans.

82

Which of two is more basic N(CH3)3 or N(SiH3)3 ? N(CH3)3

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SILICATES : Q.115 What is the hybridisation state of Si in SiO2 ? Ans. sp 3 Q.116 What happens when SiO2 is reacted (heated) with alkalis and alkali metal carbonates ? Ans. Silicates are formed Q.117 KNO3 on heating produce KNO2 and O2 but what happens when KNO3 is heated with SiO2 ? Ans. KNO3 + SiO2 → K2SiO3 + 2NO2 + ½O2 Q.118 What happens when SiO2 is reacted with following ? Ans.

(a) KOH (b) CaCO3 (c) KNO3 2KOH + SiO2 → K2SiO3 + H2O

(d) HF

(e) Coke

CaCO3 + SiO2 → CaSiO3 + CO2

2KNO3 + SiO2 → K2SiO3 + 2NO2 + ½O2 SiO2 + 6HF → H2SiF6 + 2H2O C + SiO2 → CO2 + Si

Q.119 What happens when Si is fused with NaOH in air ? Ans. Si + 2NaOH → NaSiO3 + H2↑ Q.120 What is the definition of glass ? Ans. Super cooled liquid, pseudo solid. Q.121 What type of glass is K2O.PbO.4SiO2 ? Ans. Flint Q.122 What is the formula of soda glass ? Ans. Na2SiO3.CaSiO3.HSiO2 Q.123 What is the formula of water glass Ans. Na2SiO3.H2O Q.124 What is Crookes glass ? What is its speciality ? Which metal compound is present in it ? Ans. Stops U.V. light Q.125 What is Na2SiO3. CaSiO3.4SiO2 ? Ans. Soda glass Q.126 What do you call K2O.CaO.4SiO2 ? Ans. Hard glass Q.127 Ans.

Which type of anions are present in pyrex glass ? SiO4–4, BO3–3

Q.128 How borosilicate glass are obtained ? Ans.

∆

CaCO3 + Na2CO3 + SiO2 + H3BO3   → borosilicate gass

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Q.129 Which type of glass has lane thermal expansion ? Ans. Pyrex glass Q.130 Which type of glass are prisms and lenses are made up of ? Ans. Flint glass Q.131 Name an acid which dissolves silica ? Ans. HF Q.132 Why HF acid is stored in plastic bottles and not glass bottles ? Ans. SiO2 + 6HF → H2SiF6 + 2H2O Q.133 Which compound is formed when glass reacts with HF ? Ans. Fluoro siliclic acid. Q.134 Which acid is used for etching glass ? Ans. HF Q.135 What pseudo solids ? Ans. Glass Q.136 What hapend when SiCl4 is subjected to strong heating ? Ans. When SiCl4 is heated with hot alkali, it produces orthosilicate anions which further polymerises in to slica Si

Cl Cl

Cl

Si

Cl

NaOH  → Room temp

OH OH

OH

Si

OH

Si O

O

Si

 →

O Si

O Si

Q.137 What is the formula of orthosilicate anion ? Why is it important. Ans. Orthosilicate anion-SiO44– It is the basic unit of all silicate. –

O

–

O

84

–

O

Si

O

–

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