Which are the most numerous in North America?

24-karat gold is considered to be pure gold. 18-karat gold is considered to be about 75% gold. what is 18-karat gold considered a mixture rather than a pure substance? a) it has a variable composition of other elements and minerals. b) its color is different than pure gold. c) the gold atoms are not arranged in a repeating pattern. d) it can be melted and transformed into a different substance.

Which type of antidepressant is matched with the correct neurotransmitter action? tricyclicsincrease activity of neurotransmitter gaba ssrisprevent neurotransmitter breakdown ssrisinhibit reuptake of serotonin mao inhibitorsincrease norepinephrine

Carbon tetrachloride is a toxic liquid. a carbon tetrachloride molecule has one atom of carbon and four atoms of chlorine. what is its chemical formula?