When 15 gm of NaCl and Na2CO3 is heated with dilute HCl, 2.5 gm of CO2 is evolved at NTP. Calculate percentage composition of the original mixture.

Brass is an alloy of Cu-Zn. A sample of brass weighing 6.0 g, when treated with excess of dil. H2SO4 gives 328 mL of dry H2 at 27°C and 760 mm pressure. What is the percentage of Cu by weight in the alloy? (Atomic mass of Zn = 65.4 gm)

A mixture of FeO and Fe2O4 when heated in air to constant weight gain 5% in its weight, The % of FeO in sample is?