What is the ratio of H+ ions to OH-ions at a pH = 11?

What is the relation between concentration of reactants and the rate of chemical reaction?

The number of neutrons is equal to the atomic number minus the atomic mass. a. true b. false

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?