What alkaline earth metal with a mass of 1 g was dissolved in water if 0.56 liters of hydrogen were released.

Let us write down the general equation of the reaction of the interaction of alkaline earth metals with water (alkaline earth metals are metals of the 2nd group of the main subgroup, i.e. bivalent)
1 g 0.56 l
Me + 2H2O = Me (OH) 2 + H2
x g 22.4 l
x = 1 * 22.4 ÷ 0.56 = 40 g
so we found the molar mass of the metal. we find according to the periodic table a metal of group 2 with a mass of 40 g / mol. This is calcium. Ca