What is the first step to solving a problem ?

What is a metal replacement reaction

Which ocean zone has the most abundant primary producer and why a) the abyssopelagic zone ,du to the absence of light and cold water temperatureb) the bathypelagic zone, due to the absence of light and cold water temperaturec) the mesopelagic zone ,due to uts high light availability and warm water temperature d) the epipelagic zone,due to its high light availability and warm water temperature

Achemical reaction is done in the setup shown , resulting in a change of mass. what will happen if the same reaction is done in a sealed container that is placed on the electronic balance?