Pls help ill mark as brainliest Q8. Na2CO3 Na2O + CO2

is this combustion, synthesis, single replacement, double replacement, or decomposition ?

A2.5% (by mass) solution concentration signifies that there is a 2.5 % (by mass) solution concentration signifies that there is blank of solute in every 100 g of solution. of solute in every 100 g of solution