P block Flashcards
Diborane and boron oxide react with NH3 to give what?
Boron Nitride
Does boron or HBF4 react with NH3 to give Boron nitride?
No
True or False
Does AlCl3 sublimes at 100°C under vaccum
True
Al(CH3)3 has the three centre two electron bonds in its dimeric structure (True/False)
True
BF3 reacts with NaH at 450K to give?
B2H6 + NaF
Preparation of B2H6 from NaBH4 and BF3?
3NaBH4 + 4BF3 (450K) =====> NaBF4+ 2B2H6
pH of the buffer of aqueous solution of Borax?
9
Give preparation of diborane through the reaction of NaBH4 and I2.
2NaBH4 + I2 =====> B2H6 + 2NaI + H2
Strongest back bonding in which boron halide?
BF3
In Hall heroult’s process, electrolyte is Al2O3?
True
Heating aqueous solution of aluminium chloride to dryness gives?
AlCl3
In Borax, all boron atoms lie in same plane?
False
2X + B2H6 =====> [BH2X2] + [BH4(-)]
X can be
A) NH3
B) CH3NH2
C) (CH3)2NH
D) (CH3)3N
A,B,C
Why Al(OH)3 is amphoteric in nature?
Because Al–O and O—H bonds can be broken with equal ease.
Which has is liberated on action of Aluminium with conc. NaOH?
H2
Aluminium sulphide gives a foul odour when it becomes damp. Give balanced chemical equation.
Al2S3 + 6H2O ====> 2Al(OH)3 + 3H2S
(rotten egg smell)
How is Boron obtained from Borax?
Give equations
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
Rxn of Al with aqueous NaOH. Give equations.
2Al+ 2NaOH + 2H2O ===> 2NaAlO2 + 3H2
Rxn of AlBr3 with H3PO4 and K2Cr2O7
AlBr3 + K2Cr2O7+ H3PO4 => K3PO4 + AlPO4+ H2O + Cr(3+) + Br2
C-C bond length is maximum in?
1) diamond
2) C60
3) C70
4) graphite
Diamond
Amorphous form of silica?
Keiselguhr
C60 is an allotrope of how many hexagons and pentagons?
20 hexagons and 12 pentagons
Does silicon existas covalent crystals in solid state?
True
Does CCl4 get hydrolysed?
No
In silicon dioxide, the structure is..
Each silicon atom is surrounded by 4 oxygen atoms and each O atom is bonded to 2 silicon atoms.
The material used in solar cells contains?
Cs and Si
Silicone is used as sealant?
True
Is Carbon tetrachloride inflammable?
No
Products formed when PbO2 and HCl react?
PbO2 + 4HCl => PbCl2 + Cl2 + 2H2O
Reaction involved in preparation of tin metal from cassiterite?
SnO2 + 2C ==> 2CO + Sn
Preparation of crystalline silicon from SiCl4?
3SiCl4 + 4Al ==> 4AlCl3 + 3Si
PbS(heat in air) ==> products?
PbO and PbS
PbS(heat in absence of air)===> products?
Pb + SO2
Equations for preparing anhydrous aluminium chloride from alumina.
Al2O3 + 3C + 3Cl2 –(heat)—> 2AlCl3 + 3CO
HCO3(-) + Al(3+)
HCO3(-) + Al(3+) —–> Al(OH)3 + CO3(2-)
Does PbCl2 dissolve on adding excess of HCl.
Yes.
Due to formation of PbCl4
Is Boric acid protonic acid?
No
Lithium Aluminium Hydride reacts with silicon tetrachloride to give.
LiCl+ AlCl3+ SiH4
Does silicon dioxide exhibit polymorphism?
Yes
Structure of silicates in which three oxygen atoms of SiO4 are shared is
Sheet silicate
In freezing winter, white metallic tin gets converted to grey powder. This happens because…
A change in crystalline structure of tin
Pb and Sn are extracted from their chief ores by
Self reduction and carbon reduction respectively
Is SnCl.2H2O a reducing agent ?
True
Does SnO2 react with KOH to form K2[Sn(OH)6]?
Yes
The reaction of Pb3O4 with dilute nitric acid to give PbO2 is a redox reaction.
False
Pb3O4 + 4HNO3 ===> PbO2 + 2Pb(NO3)2 + 2H2O
This reaction is not redox
Pb3O4 is a mixture of PbO and PbO2
SnCl2 + Cl(-) ===> ?
SnCl2 + Cl(-) ===> SnCl3(-)
SnCl2 + Me3N ===> ?
SnCl2 + Me3N ===> SnCl2.[N(CH3)3
SnCl2 + 2CuCl2 ===>
SnCl2 + 2CuCl2 ===> SnCl4 + 2CuCl
Is Cs used in photoelectric cells?
Yes
Ga used in high temperature thermometers?
True
B used in bullet proof vests?
True
Si used in water repellent spray?
True
What is litharge ?
PbO
Reaction involved in extraction of Pb?
2PbS + 3O2 ===> 2PbO + 2SO2
PbS + O2 ===> PbSO4
PbS + 2PbO ===> 3Pb + SO2
PbS + PbSO4 ===> 2Pb + 2SO2
Rxn SnCl4 with ethyl chloride?
SnCl4 + 2C2H5Cl +2Na ===> C4H10 + 2Na2[SnCl6]
Sn + KOH + 4H2O ===>
Sn + KOH + 4H2O ===> K2Sn(OH)6 + 2H2
Prepare Si from SiCl4?
SiCl4 + 2Mg(or Zn) ===> Si+ 2MgCl2(or ZnCl2)
SiCl4 + CH3MgCl gives
SiCl3(CH3)
Prepare Na2SiO3 from SiCl4?
SiCl4 + 4H2O ===> Si(OH)4
Si(OH)4 ===> SiO2 + H2O
SiO2 + Na2CO3 ===> Na2SiO3+ 2Na2[SnCl6]
A + alkali ==> B (Major product)
If B is an oxoacid of phosphorus with no P-H bond, then A is
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(+)
White phosphorus reacts with thionyl chloride to give?
PCl3 + SO2+ S2Cl2