I dont know what subject is this
Answer:
A cold front forms when a cold air mass pushes into a warmer air mass. Cold fronts can produce dramatic changes in the weather. ... As the cold front passes, winds become gusty. There is a sudden drop in temperature, and also heavy rain, sometimes with hail, thunder, and lightning.
Answer: The first plastic based on a synthetic polymer was invented in 1907. Plastic sticks around in the environment for ages, threatening wildlife and spreading toxins.
The drawing is correct because there are 12 atoms of each type on each side of the arrow.