Question

which of these elements has the largest atomic radius and which one is least reactive

Answer 1

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Answer 2

Reflecting telescopes use mirrors instead of lenses to collect light. Because mirrors have only one reflective surface, they are easier to construct than lenses, which are made from optical glass, and cannot have any occlusions because light must pass completely through them. In addition, mirrors have less spherical aberration, which is a scattering of light that occurs when lenses don't perfectly focus on a single point. Mirrors also reflect all wavelengths of light equally, whereas lenses bend light differently depending on its wavelength.