This passage describes a chemical reaction. Read the passage. Then, follow the instructions
below.
Like people on Earth, astronauts living on the International Space Station need
oxygen to survive. Since there is no oxygen in space for the astronauts to breathe,
they make oxygen using a process called electrolysis. This process uses electricity to
break down water into hydrogen gas and oxygen gas. The hydrogen gas can be
removed from the space station or recycled, and the oxygen gas is released into the
air that the astronauts breathe.
Complete the sentence.
In this chemical reaction, hydrogen