input question: What is the missing first step of the following process: - Is exposed to air - A chemical reaction occurs - The iron starts to oxidize - The iron starts to rust.???
output answer: Iron is exposed to oxygen

What is the missing first step of the following process: - The roots absorb water and minerals from the soil - This combination of water and minerals flows from the stem into the leaf - Carbon dioxide enters the leaf - Light, water and minerals, and the carbon dioxide all mix together - This mixture forms sugar (glucose) which is what the plant eats - Oxygen goes out of the leaf through the stomata -
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Answer: Chloroplasts in the leaf of the plant traps light from the sun

Q: What is the missing first step of the following process: - Two types of proteins exist in filaments in the muscles - The filaments move when the brain instructs them to - The motion of the filaments cause the muscle to shorten and contract - Opposing pairs of muscles exist in order to provide the necessary range of motion.
A: Electrical signals in the brain travel through nerves to muscles

Question: What is the missing first step of the following process: - The virus enters the human or animal body - The virus goes to the part of the body that contains its food - The virus consumes part of the body or materials that the body uses - The virus replicates and spreads - The virus causes symptoms in the body as the immune system tries to expel the virus.
Answer: Contact is made with a virus

[Q]: What is the missing first step of the following process: - The seeds are dispersed by wind, animals, etc - The seeds reach the ground - Grow into new trees - These new trees produce seeds - The process repeats itself over and over -
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[A]: A tree produces seeds

Problem: Given the question: What is the missing first step of the following process: - These substances rise into the high atmosphere - They react with water and oxygen - This creates a more acidic rain - The rain with the high acid content falls.
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The answer is:
Chemicals like sulfur dioxide and nitrogen are released into the air