Hydrogen is a pure substance represented by the chemical symbol H. Which of the following best describes hydrogen?
A. Hydrogen is a compound made of two or more kinds of atoms.
B. Hydrogen is an element made of only one kind of atom.
OC. Hydrogen is an element made of two or more kinds of atoms.
D. Hydrogen is a compound made of only one kind of atom.

Infants born with severe respiratory problems are sometimes given liquid ventilation: they breathe a liquid that can dissolve more oxygen than air can hold. one of these liquids is a fluorinated compound, cf3(cf2)7br. the solubility of oxygen in this liquid is 66 mlo2 per 100 ml liquid. in contrast, air is 21 % oxygen by volume. calculate the moles of o2 present in an infant's lungs (volume: 12 ml ) if the infant takes a full breath of air. assume a pressure of 1 atm in the lungs.

Elements that do not have full outer electron shells will donate, share, or take electrons from other atoms. choose the items that have the correct binary ionic formula.

Asolution contains 180 g of glucose (c6h12o6) and 162 g of water. what is the mole fraction of glucose?