The universe is about 15 billion years old (15000 million) what percentage of THAT time has the Earth been in existence?​

There are specialized producers that live in warm water vents deep in the ocean. these producers do not per-form from photosynthesis, but instead perform a similar process with iron and other chemicals. why do you think these producers use this process instead of photosynthesis?

Brass gets discoloured in air because of the presence of which of the following gases in air? a. oxygen b. hydrogen sulphide c. carbon dioxide d. nitrogen

Which part of the microscope controls the amount of light which shines through the lens?