P block Flashcards

1
Q

Diborane and boron oxide react with NH3 to give what?

A

Boron Nitride

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2
Q

Does boron or HBF4 react with NH3 to give Boron nitride?

A

No

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3
Q

True or False
Does AlCl3 sublimes at 100°C under vaccum

A

True

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4
Q

Al(CH3)3 has the three centre two electron bonds in its dimeric structure (True/False)

A

True

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5
Q

BF3 reacts with NaH at 450K to give?

A

B2H6 + NaF

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6
Q

Preparation of B2H6 from NaBH4 and BF3?

A

3NaBH4 + 4BF3 (450K) =====> NaBF4+ 2B2H6

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7
Q

pH of the buffer of aqueous solution of Borax?

A

9

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8
Q

Give preparation of diborane through the reaction of NaBH4 and I2.

A

2NaBH4 + I2 =====> B2H6 + 2NaI + H2

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9
Q

Strongest back bonding in which boron halide?

A

BF3

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10
Q

In Hall heroult’s process, electrolyte is Al2O3?

A

True

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11
Q

Heating aqueous solution of aluminium chloride to dryness gives?

A

AlCl3

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12
Q

In Borax, all boron atoms lie in same plane?

A

False

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13
Q

What kind of units are present in Borax?

A

Tetranuclear units B4O5(OH)4

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14
Q

2X + B2H6 =====> [BH2X2] + [BH4(-)]
X can be
A) NH3
B) CH3NH2
C) (CH3)2NH
D) (CH3)3N

A

A,B,C

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15
Q

Why Al(OH)3 is amphoteric in nature?

A

Because Al–O and O—H bonds can be broken with equal ease.

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16
Q

Which has is liberated on action of Aluminium with conc. NaOH?

A

H2

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17
Q

Aluminium sulphide gives a foul odour when it becomes damp. Give balanced chemical equation.

A

Al2S3 + 6H2O ====> 2Al(OH)3 + 3H2S

                               (rotten egg smell)
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18
Q

How is Boron obtained from Borax?
Give equations

A

Na2B4O7 + 2(hot conc)HCl => 2NaCl + H2B4O7
H2B4O7 + 5H2O ==> 4H3BO3
(sparingly soluble)
2H3BO3 ==> (heat strongly) B2O3 + 3H2O

B2O3 + 6K(or Na or Mg) => 2B +3K2O

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19
Q

Rxn of Al with aqueous NaOH. Give equations.

A

2Al+ 2NaOH + 2H2O ===> 2NaAlO2 + 3H2

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20
Q

Rxn of AlBr3 with H3PO4 and K2Cr2O7

A

AlBr3 + K2Cr2O7+ H3PO4 => K3PO4 + AlPO4+ H2O + Cr(3+) + Br2

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21
Q

C-C bond length is maximum in?
1) diamond
2) C60
3) C70
4) graphite

A

Diamond

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22
Q

Amorphous form of silica?

A

Keiselguhr

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23
Q

C60 is an allotrope of how many hexagons and pentagons?

A

20 hexagons and 12 pentagons

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24
Q

Does silicon existas covalent crystals in solid state?

A

True

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25
Q

Does CCl4 get hydrolysed?

A

No

26
Q

In silicon dioxide, the structure is..

A

Each silicon atom is surrounded by 4 oxygen atoms and each O atom is bonded to 2 silicon atoms.

27
Q

The material used in solar cells contains?

A

Cs and Si

28
Q

Silicone is used as sealant?

A

True

29
Q

Is Carbon tetrachloride inflammable?

A

No

30
Q

Products formed when PbO2 and HCl react?

A

PbO2 + 4HCl => PbCl2 + Cl2 + 2H2O

31
Q

Reaction involved in preparation of tin metal from cassiterite?

A

SnO2 + 2C ==> 2CO + Sn

32
Q

Preparation of crystalline silicon from SiCl4?

A

3SiCl4 + 4Al ==> 4AlCl3 + 3Si

33
Q

PbS(heat in air) ==> products?

A

PbO and PbS

34
Q

PbS(heat in absence of air)===> products?

A

Pb + SO2

35
Q

Equations for preparing anhydrous aluminium chloride from alumina.

A

Al2O3 + 3C + 3Cl2 –(heat)—> 2AlCl3 + 3CO

36
Q

HCO3(-) + Al(3+)

A

HCO3(-) + Al(3+) —–> Al(OH)3 + CO3(2-)

37
Q

Does PbCl2 dissolve on adding excess of HCl.

A

Yes.
Due to formation of PbCl4

38
Q

Is Boric acid protonic acid?

A

No

39
Q

Lithium Aluminium Hydride reacts with silicon tetrachloride to give.

A

LiCl+ AlCl3+ SiH4

40
Q

Does silicon dioxide exhibit polymorphism?

A

Yes

41
Q

Structure of silicates in which three oxygen atoms of SiO4 are shared is

A

Sheet silicate

42
Q

In freezing winter, white metallic tin gets converted to grey powder. This happens because…

A

A change in crystalline structure of tin

43
Q

Pb and Sn are extracted from their chief ores by

A

Self reduction and carbon reduction respectively

44
Q

Is SnCl.2H2O a reducing agent ?

A

True

45
Q

Does SnO2 react with KOH to form K2[Sn(OH)6]?

A

Yes

46
Q

The reaction of Pb3O4 with dilute nitric acid to give PbO2 is a redox reaction.

A

False
Pb3O4 + 4HNO3 ===> PbO2 + 2Pb(NO3)2 + 2H2O
This reaction is not redox

Pb3O4 is a mixture of PbO and PbO2

47
Q

SnCl2 + Cl(-) ===> ?

A

SnCl2 + Cl(-) ===> SnCl3(-)

48
Q

SnCl2 + Me3N ===> ?

A

SnCl2 + Me3N ===> SnCl2.[N(CH3)3

49
Q

SnCl2 + 2CuCl2 ===>

A

SnCl2 + 2CuCl2 ===> SnCl4 + 2CuCl

50
Q

Is Cs used in photoelectric cells?

A

Yes

51
Q

Ga used in high temperature thermometers?

A

True

52
Q

B used in bullet proof vests?

A

True

53
Q

Si used in water repellent spray?

A

True

54
Q

What is litharge ?

A

PbO

55
Q

Reaction involved in extraction of Pb?

A

2PbS + 3O2 ===> 2PbO + 2SO2
PbS + O2 ===> PbSO4
PbS + 2PbO ===> 3Pb + SO2
PbS + PbSO4 ===> 2Pb + 2SO2

56
Q

Rxn SnCl4 with ethyl chloride?

A

SnCl4 + 2C2H5Cl +2Na ===> C4H10 + 2Na2[SnCl6]

57
Q

Sn + KOH + 4H2O ===>

A

Sn + KOH + 4H2O ===> K2Sn(OH)6 + 2H2

58
Q

Prepare Si from SiCl4?

A

SiCl4 + 2Mg(or Zn) ===> Si+ 2MgCl2(or ZnCl2)

59
Q

SiCl4 + CH3MgCl gives

A

SiCl3(CH3)

60
Q

Prepare Na2SiO3 from SiCl4?

A

SiCl4 + 4H2O ===> Si(OH)4
Si(OH)4 ===> SiO2 + H2O
SiO2 + Na2CO3 ===> Na2SiO3+ 2Na2[SnCl6]

61
Q

A + alkali ==> B (Major product)
If B is an oxoacid of phosphorus with no P-H bond, then A is

A

A is Red P
Red P on reaction with alkali gives hypophosphoric acid.
Red p + 4NaClO2 + 4H2O(controlled oxidation)==> 2Na2H2P2O6 + 4HC
l
Na2H2P2O6 + 2H+==> H4P2O6 + 2Na(+)

62
Q

White phosphorus reacts with thionyl chloride to give?

A

PCl3 + SO2+ S2Cl2