Chloroplasts.
Always present in almost all plants because they are vital to the process of photosynthesis and primary food production. Onions are not primary producers and do not produce their own food and hence do not require this organelle!
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The (valence) electrons of an atom because they're the most moveable particles of the atom...they are found on the valence shells and can move, unlike the protons and neutrons which are enclosed in the nucleus of the atom.
<u>0.4 mol of </u> molecules has larger mass than 0.4 mol of O atoms
<h3>What are molecules?</h3>
The smallest component of a substance that possesses both its chemical and physical characteristics. One or more atoms make up molecules.
They may have the same atoms (for example, an oxygen molecule has two oxygen atoms) or different atoms if they have more than one (a water molecule has two hydrogen atoms and one oxygen atom). Biological molecules like DNA and proteins can include thousands of atoms.
the lowest recognised unit into which a pure material can be divided while retaining its chemical makeup and attributes is made up of two or more atoms.
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