For the reaction sequence given below, the correct statement(s) is(are)

(In the options, X is any atom other than carbon and hydrogen, and it is different in P, Q and R)

In an electrochemical cell, dichromate ions in aqueous acidic medium are reduced to Cr³⁺. The current (in amperes) that flows through the cell for 48.25 minutes to produce 1 mole of Cr³⁺ is ______.

Use: 1 Faraday = 96500 C mol⁻¹

At 25 °C, the concentration of H⁺ ions in 1.00 × 10⁻³ M aqueous solution of a weak monobasic acid having acid dissociation constant (K_a) of 4.00 × 10⁻¹¹ is X × 10⁻⁷ M. The value of X is ______.

Use: Ionic product of water (K_w) = 1.00 × 10⁻¹⁴ at 25 °C

Molar volume (V_m) of a van der Waals gas can be calculated by expressing the van der Waals equation as a cubic equation with V_m as the variable. The ratio (in mol dm⁻³) of the coefficient of V_m² to the coefficient of V_m for a gas having van der Waals constants a = 6.0 dm⁶ atm mol⁻² and b = 0.060 dm³ mol⁻¹ at 300 K and 300 atm is ______.

Use: Universal gas constant (R) = 0.082 dm³ atm mol⁻¹ K⁻¹