(high-use academic words the word emit means "to give off.)

1. what do vehicles that run on hydrogen fuel cells emit?
my answer

the oceanic zone is typically defined as the area of the ocean lying beyond the continental shelf, but operationally is often referred to as beginning where the water depths drop to below 100 meters (328 feet), seaward from the coast to the open ocean.

explanation:

when a reversible reaction is occurring in both directions at the same rate; the products and reactants do not change in concentration. a chemical reaction where the compound is broken into its constituent parts.

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.

is this a psat question, if so do not cheat try your best.