How many variables should you change in a controlled experiment? one two four as many as possible

What kind of crystalline solid is graphite? o a. molecular solid b. metallic solid o c. network solid d. ionic solid

An organ system consists of a group of organs that performs specific functions necessary for the survival of an organism. humans have eleven different organ systems: integumentary, skeletal, muscular, nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary, and reproductive. discuss the function of neurons, the brain and the spinal cord within the human nervous system while explaining the interrelationship of each organ.

Describe two recent or ongoing space missions.