Answer:
Electrons Can Donate - 0
Electrons Can Receive- 2
Valence - 2
Explanation:
The electronic configuration of oxygen is 
. Thus in the p-orbital there is deficiency of two electrons. Hence, it can receive/share electron but it cannot donate electrons. This makes oxygen as a good electron acceptor. Since there is a deficiency of two electrons in the outermost shell of oxygen, the valence of oxygen in thus -2
A good extraction solvent should have a strong solubilizing capability for the compound of interest, it should be immiscible or only weakly misciblewith the matrix solvent ( the first solution or mixture containing the compound from its natural source, e.g., water/ether. water/ chloroform, etc. If possible the extraction solvent should be non-flammable, non-toxic or of low toxicity, reasonably volatile, and of low eco-impact. Inexpensive and available, of high purity , and shelf stable. If one is determining the compound of interest by UV/Vis spectrophotometry or fluorescence, the solvent should have extremely low absobance or emission at the wavelength of analysis
• high solubility for the solute and low solubility for the carrier liquid.
• density difference vs. the carrier liquid greater than 150 kg/m. ...
• mid-level interfacial tension (5–30 dyne/cm)
• high resistance to thermal degradation.
I believe that the right answer is Heat energy
Rain forest contains more species
