Calculate the mass of sodium carbonate when 16.8g of sodium hydrogen carbonate is heated strongly until there is no further change. The equation for the reaction is: (5marks) NaCO3(s) + CO2(g) + 2 NaHCO3(s) H2O(g) :

The human activities in two locations are described below: location a: rampant use of plastic containers location b: excessive use of pesticides and fertilizers which statement is most likely true? location a will have poor air quality because plastic is biodegradable. location a will experience water scarcity because plastic absorbs moisture. the population of honeybees will increase in location b because production of crops will increase. the population of fish in location b will decrease because the water is contaminated.