A mixture of two solid elements with a mass of 1.52g was treated with an excess of hydrochloric acid. A volume of 0.896 dm^(3) of a gas was liberated in this process and 0.56 g of a residue remained which was undissolved in the excess of the acid. In another experiment, 1.52 g of the same mixture were allowed to react with an excess of a 10% sodium hydroxide solution. In this case 0.896 dm^(3) of a gas were also evolved but 0.96 g of an undissolved residue remained. In the third experiment, 1.52 g of the initial mixture were heated to high temperature without acess of the air. In this way a compound was formed which was totally soluble in hydrochloric acid and 0.448 dm^(3) of an unknown gas were released. All the gas obtained was introduced into a one litre closed vessel filled with oxygen. After the reaction of the unknown gas with oxygen the pressure in the vessel decreased by approximately ten times (T=const). Write chemical equations for the above reactions and prove their correctness by calculations. In solving the problem consider that the volumes of gases were measured at STP and round up the relative atomic masses to whole numbers.