Which concentration of alcohol is deemed most effective in alcohol-based hand cleaners?

Which element is used in photosynthesis found in atmosphere and fixed by bacteria?

In iceland, the mid atlantic ridge runs through the center of the contry. what can you conclude about the apperence of iceland many thousands of years from now?

When coal has reached it hardest, darkest form, it is called select one: 0 a. sub-bituminous b. lignite c. bituminous d. antrhacite next page