By usual analysis, 1.00 g of compound (X) gave 1.79 g of magnesium pyrophosphate. The percentage of phosphorus in compound (X) is : (nearest integer)

(Given, molar mass in g mol⁻¹: O = 16, Mg = 24, P = 31)

Aqueous HCl reacts with MnO₂(s) to form MnCl₂(aq), Cl₂(g), and H₂O(l). What is the weight (in g) of Cl₂ liberated when 8.7 g of MnO₂(s) is reacted with excess aqueous HCl solution? (Given Molar mass in g mol⁻¹ Mn = 55, Cl = 35.5, O = 16, H = 1)

14.0 g of calcium metal is allowed to react with excess HCl at 1.0 atm pressure and 273 K . Which of the following statements is incorrect?

[Given : Molar mass in $\mathrm{g} \mathrm{mol}^{-1}$ of $\mathrm{Ca}-40, \mathrm{Cl}-35.5, \mathrm{H}-1$ ]

On combustion 0.210 g of an organic compound containing C, H and O gave 0.127 g H₂O and 0.307 g CO₂. The percentages of hydrogen and oxygen in the given organic compound respectively are: