sulfides

"The prisoners were kept in a secure compound. "

"While walking to school, Sarah found a lost wallet on the ground. "

"The mining company explored for metal ores in the remote mountain ranges. "

"Letters are the elements of written language."

"I will not remain here any longer."

"The science lab contained a sample of sulfur. "

"a blood sample"

"She gave a studied reply."

"In the electrolysis of saltwater, the electropositive (sodium ion) migrates to the negatively charged cathode. "

"My brother is a different person; he's an other, not like me at all. "

"The group of students worked together on their project. "

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