Which of the following is most stable ?
Sn2+
Ge2+
Si2+
Pb2+
Which of the following is a component of ruby?
CaCO3
MgCO3
Al2O3
Al(OH)3
Graphite is a soft, solid lubricant,extremely difficult to melt. The reason for this anamolous behaviour is that, graphite
is an allotropic form of diamond
has molecules of variable molecular masses like polymers
has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak inter plate bonds
is a non-crystalline substance.
A hydride of nitrogen which is acidic is
NH3
N2H4
N2H2
N3H
For making good quality mirrors, plates of flint glass are used. These are obtained by floating molten glass over a liquid metal which does not solidify before glass. The metal used can be
Tin
Sodium
Magnesium
Mercury
Alum is widely used to purify water since
It forms complex with clay particles
It coagulates the mud particles
It exchanges Ca2+ and Mg2+ ions present in hard water
Its sulphate ion is water purifier.
In curing cement plasters water is sprinkled from time to time.This helps in
keeping it cool
developing interlocking needle like crystals of hydrated silicates
hydrating sand and gravel mixed with cement
converting sand into silicic acid
Carbogen is
mixture of O2 + 5 - 10% CO2.
used by pneumonia patient for respiration
used by victims of CO poisoning for respiration
All of the above
When concentrated HNO3 is heated with P2O5, it forms
N2O
NO
NO2
N2O5
Of the following compounds, the most acidic is
AS2O3
P2O5
Sb2O3
Bi2O3