Hydrogen is placed separately from the other elements in the periodic table because it A. Is a gas
B. Has atomic number 1
C. Has many unique properties
D. Does not exist as a free element in nature

Ageologist determines that a sample of a mineral can't be scratched by a steel nail but can be scratched by a masonry drill bit. based on this information, the sample mineral has to be softer than a. orthoclase. b. fluorite. c. apatite. d. corundum.

When balancing a chemical equation:

May someone me with these science questions