Do you know any element which have no neutron in its atom?

Which change in temperature is the smallest? a change of 1 thomson degree a change of 1 kelvin degree a change of 1 fahrenheit degree a change of 1 celsius degree

Areaction in which products can react to re-form reactants is

Before it was launched, a helium-filled balloon had a pressure of 201 kpa at a temperature of 27°c. at an altitude of 15,000 m, the pressure had decreased to 2.5 kpa and the temperature had dropped to -14 °c. the volume of the balloon increased to 59.3 m3. what is the original volume of the balloon? 13 m3 0.85 m3 0.077 m3 1.17 m3