This chemical element was discovered independently by Carl Wilhelm Scheele in 1773 and Joseph Priestley in 1774. The latter is often given priority because his work was published first. Which element?

What is a hydrogen atom with two neutrons in the core called?

We breathe this chemical element every day and with each breath we take. Which number in the periodic table has oxygen?

Which chemical element is the lightest, but at the same time it is estimated to take up 3/4 of the Universe's mass?