CBSE
Multiple Choice QuestionsMany compounds are formed by carbon atom because of its :
more reactivity
covalent and ionic nature
variable valency
catenation nature
Which of the following elements will have the highest electron affinity ?
Chlorine
Nitrogen
Phosphorus
Fluorine
Reaction of diborane with ammonia gives initially :
B2H6 . NH3
borazole
B2H6 . 3NH3
[BH2(NH3)2]+ [BH4]-
Select the correct options from the following :
Graphene is an atomic layer of graphite
Graphene is an atomic layer composed of sp2-hybridised carbon.
Chemical bonds in graphite are similar in strength to that of diamond.
All of these.
Iodine oxidises sodium borohydride to give
B2H6
sodium hydride
HI
I3-
The wrong statement about fullerene is
it has 5-membered carbon ring
it has 6-membered carbon ring
it has sp2 hybridization
it has 5-membered rings more than 6-membered rings
Assertion: Conductivity of silicon increases by doping it with group-15 elements.
Reason : Doping means introduction of small amount of impurities like P, As or Bi into the pure crystal.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Addition of group-13 elements to intrinsic semiconductors results in
creation of conduction band slightly above the valence band
creation of conduction band slightly below the valence band
creation of valence band slightly above the conduction band.
overlapping of valence band and conduction band
If Si is doped with B,
n-type semiconductor is formed
p-type semiconductor is formed
insulator is formed
polymer is formed.
For silicon which is not correct?
It is a type of silicate.
It is thermally unstable.
It is hydrophilic.
Repeating unit is R2SiO.
