Which structure is found in some but not all plant cells? a. vacuole b. ribosome c. cell wall d. lysosome​

What two factors can affect the properties of a hydrocarbon? a. the number of its carbon atoms and the number of single bonds b. the number of its carbon atoms and the arrangement of its atoms c. the arrangement of its atoms and the number of its double bonds

Which change will decrease the number of effective collisions during a chemical reaction? a. adding a catalyst b. increasing the surface area c. decreasing the temperature d. increasing the reactant concentrations e. increasing the volume of the reactants

If you try to move a piano and are unable to move it, did you perform any work in the scientific sense of the word? yes or no?