arsenic

"Sulfur trioxide, a dangerous pollutant, is released during the burning of some fuels. "

"The teacher isolated the student who was disruptive, placing him in a separate room. "

"The science teacher conducted an experiment to demonstrate how plants grow in different types of soil. "

"Any painter can benefit from the presence of a live model from which to draw."

"The box containing my old toys was stored in the attic. "

"He listened carefully to his mother's concerns, feeling sorrowful about her disappointment. "

"Phosphorus is described as pentavalent because it can form five chemical bonds with other atoms. "

"The research station that houses Wang and his team is outside Lijiang, a city of about 1.2 million people."

"The guard blew his whistle to indicate imminent departure."

"The scientist studied the effects of different types of soil on plant growth. "

"The scientist studied the chemical composition of the soil sample. "

""During the war, the refugees lived in guarded compounds for their safety." "