What will a presumptive test find?

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?

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 ?

Salt in oceans comes from and of rocks