Hydrogen is a pure substance represented by the chemical symbol h. which of the following best describes hydrogen?
a. hydrogen is an element made of only one kind of atom.
b. hydrogen is a compound made of two or more kinds of atoms.
c. hydrogen is an element made of two or more kinds of atoms.
d. hydrogen is a compound made of only one kind of atom.
b

The observations of hooke and van leeuwenhoek documenting the existence of microscopic cells formed the basis of what important theory? a. the cell theory stating that all living things are composed of cellsb. the theory of spontaneous generation, which held that life forms could arise spontaneouslyc. the theory of chemotherapy, or use of antimicrobials to destroy pathogenic organismsd. the germ theory of disease and causative agents

Akrabby blind whale has married pearl who has normal vision. oneof their two sons is also colorblind. what arr the genotypes of the parents?

Why are fossils not found in igneous rocks? igneous rocks are made from cooling of lava or magma. igneous rocks are found too deep underground. igneous rocks are too dark in color to contain fossils. igneous rocks are too dense to contain fossils.