Which subatomic particle has a negative charge and the smallest mass?

A water sample contains 5 mg of dissolved chloride ions per liter of solution. This concentration is equivalent to:

Which type of radioactive emission has NO mass and NO charge, consisting of high-energy electromagnetic radiation?

Which statement about an ideal gas is TRUE according to the kinetic molecular theory?

The reaction 2 H₂(g) + O₂(g) → 2 H₂O(l) is best classified as which type of reaction?