Carbón Dioxide is . A. Element
B. Composite
C. Homogeneous mixtures
D. Heterogeneous mixtures

Carbon dioxide is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules consist of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmosphere as a trace gas.

Explanation:

Answer corrected but hope it helped

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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answer: a) a compound microscope has a greater magnification ability than a simple microscope.

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