4. A
because PbCl2 is an ionic compound and it's solid, so it's a substance.
It cannot be mixture, because it's a pure molecule.
5. D
despite that both substances are gases, colorless they are different molecules, so they should have different either chemical and physical properties
6. C
this substance made from W atoms and others are made from molecules
You convert kinetic energy into thermal energy when you rub two sticks together.
Answer:
potassium contains both Ionic and covalent bonds
Answer:
When there is less carbon (in the form of carbon dioxide) in abiotic matter, less carbon is available for producers making energy storage molecules. When there is more sunlight, producers can make more energy storage molecules from the carbon in carbon dioxide.
Hope this helps.
