Which of the following will replace Br2 from the aqueous solution having bromide ion?
Cl2
I
I2
Cl
If 2.0 g of a radioactive substance has half-life of 7 days, the half-life of 1 g sample is
7 days
14 days
28 days
35 days
According to the adsorption theory of catalysis the speed of the reaction increase because
the concentration of reactant molecules at the active centres of the catalyst becomes high due to adsorption
in the process of adsorption, the activation energy of the molecules becomes large
absorption produces heat which increases the speed of the reaction
adsorption lowers the activation energy of the reaction
In the metallurgy of which of the following cupellation process is used?
Copper
Silver
Iron
Aluminium
Cryolite is used in the electrolytic extration of aluminium
to obtain more aluminium
to decompose bauxite
to protect anodes
as a reducing agent
B.
to decompose bauxite
Cryolite is used in the electrolytic extraction of aluminium to decompose bauxite.
3NaF + AlF3
AlF3 Al3+ + 3F-
At cathode
Al3+ + 3e- → Al (l)
At anode
2Al2O3 + 12F- → 4AlF3 + 6O2-
C (s) + O2- → CO (g) + 2e-
C (s) + 2O2- → CO2 (g) + 4e-
Which element from group V gives most basic compound with hydrogen?
Nitrogen
Bismuth
Arsenic
Phosphorus
Point out in which of the following properties oxygen differs from the rest of the members of its family (Group-VIA)?
High value of ionisation energies
Oxidation states (2,4,6)
Polymorphism
Formation of hydrides
Which of the following properties increases on going down from F to I in group VII-A of the periodic table?
Electronegativity
Volatile nature
Ionic radius
Oxidising power