Compounds, and Mixtures An element is a pure substance containing:
only one kind of atom
two or more kinds of atoms
two or more kinds of compounds
a mixture
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Answerit curves up and levels out.explanationwe assume that the container contains absolutely no ammonia to begin with as it states that "nitrogen gas and hydrogen gas" react to "produce ammonia."at dynamic equilibrium, the product and reactant concentrations are equal.this means that, starting from a concentration of zero, [nh₃] must curve "up" from zero and then level out to a constant concentration.