The following results were obtained during kinetic studies of the reaction ;

2A + B $$ \to $$ Products

Experiment	[A] (in mol L$$-$$1)	[b] (in mol L$$-$$1)	Initial Rate of reaction (In mol L$$-$$1 min$$-$$1)
I	0.10	0.20	6.93 G 10$$-$$3
II	0.10	0.25	6.93 G 10$$-$$3
III	0.20	0.30	1.386 G 10$$-$$2

The time (in minutes) required to consume half of A is :

For emission line of atomic hydrogen from n_i = 8 to n_f = n, the plot of wave number $$\left( {\overline v } \right)$$ against $$\left( {{1 \over {{n^2}}}} \right)$$ will be (The Rydberg constant, R_H is in wave number unit)

20 mL of 0.1 M H₂SO₄ solution is added to 30 mL of of 0.2 M NH₄OH solution. The pH of the resultant mixture is : [pk_b of NH₄OH = 4.7].

Aluminium is usually found in +3 oxidation state. In contrast, thallium exists in + 1 and + 3 oxidation states. This is due to :