instruction:
In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
question:
Ozone leaves _ by-products except pure oxygen.
answer:
no


question:
Sediment consists of _ visually distinct floc layers.
answer:
two


question:
Heme is made of _ pyrrole groups united to form a porphyrin ring.
answer:

four