Answer:b.CaCl2
Explanation:
A compound is a substance resulting when two or more elements are are chemically bonded together either ionically or covalently in a fixed ratio.
From the given options we can see that the only compound there is CaCl2 which is an ionic compound in the fixed ratio of one calcium ion to two chloride ions.
Other options , Cu,Na and Nd are merely pure substance---Elements
It would be 24 because they inherit half of there chromosomes from their dad and the other half from their mom<span />
It respresents the higher energy level than 627nm .
<h3>What is a emission line ? </h3>
Emission lines are the glowing hot gas emits lines of light whereas absorption line refers to the tendency of cool atmospheric gas to absorb the same line of light.Some lights produce dark band when the light passes through gas in the atmosphere . There are two line spectrum and absorption.
spectrum is an excitement of electrons from lower to higher energy levels and when it comes back it releases energy in the terms of colourful lights .
It represents the higher energy levels than 627nm because Energy is inversly proportional to wavelength .
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The change is that the water will freeze to 0 or minus I don’t know as I’m not to sure
