What is the net charge of Se2-?

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.

i don't understand. explain it clearly

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myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.