For the following reaction,
$$2X + Y\buildrel k \over \longrightarrow P$$ the rate of reaction is $${{d[P]} \over {dt}} = k[X]$$. Two moles of X are mixed with one mole of Y to make 1.0 L of solution. At 50 s, 0.5 mole of Y is left in the reaction mixture. The correct statement(s) about the reaction is(are)

(Use : ln 2 = 0.693)

Some standard electrode potentials at 298 K are given below :

Pb²⁺ /Pb = $$- $$0.13 V

Ni²⁺ /Ni = $$-$$ 0.24 V

Cd²⁺ /Cd = $$-$$ 0.40 V

Fe²⁺ /Fe = $$-$$ 0.44 V

To a solution containing 0.001 M of X²⁺ and 0.1 M of Y²⁺, the metal rods X and Y are inserted (at 298 K) and connected by a conducting wire. This resulted in dissolution of X. The correct combination(s) of X and Y, respectively, is(are)

(Given : Gas constant, R = 8.314 J K^$$-$$ mol^$$-$$1, Faraday constant, F = 96500 C mol^$$-$$1)

The pair(s) of complexes wherein both exhibit tetrahedral geometry is(are)

(Note : py = pyridine)

Given : Atomic numbers of Fe, Co, Ni and Cu are 26, 27, 28 and 29, respectively)

The correct statement(s) related to oxoacids of phosphorous is(are)