A marine biologist is preparing a deep-sea submersible for a dive. The sub stores breathing air under high pressure in a spherical air tank that measures wide. The biologist estimates she will need of air for the dive. Calculate the pressure to which this volume of air must be compressed in order to fit into the air tank. Write your answer in atmospheres. Be sure your answer has the correct number of significant digits.

The chemical bubbles

Combustion is the act or process of burning. therefore, i believe the answer is  a: burning wood. 

In reversible reaction chemistry equilibrium is attained when the forward and reverse reactions are taking place at the same rate, thus, the concentrations of reactants and products remain the same. a reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back. in irreversible reactions on the other hand, the reactants react to form the products, which cannot revert back into reactants.