90 grams due to laws of conservation of mass. Input mass always = output mass. It may come out in a different form but it's always the same mass.
If by Period you mean Column, they share the same amount of electrons in their outer shell.
Enter a chemical formula to calculate its molar mass and elemental composition: Notice: your ... as a zero '0' Molar mass of Na2Co3*10H2O<span> is 402.9319 g/mol ...</span>