Which of the following is an example of a chemical change that occurs during weathering? O Freezing and thawing of water in the cracks of rocks
O Animals dig a hole in the ground looking for worms
O Flowing water smooths rock surfaces in a river
O Acids from the lichens growing on the rock breaks down the rock into soil

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Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?

Which statement justifies that hydrogen peroxide (h2o2) is a polar molecule? the o – h bond is nonpolar and the molecule is asymmetric. the o – h bond is nonpolar and the molecule is symmetric. the o – h bond is polar and the molecule is asymmetric. the o – h bond is polar and the molecule is symmetric.