Produces heat, putting off air or bubbles and changes the smell or odor it changes the state that’s how you know it is a chemical reaction
Http://chemistry.about.com/od/chemistryterminology/a/What-Is-The-Difference-Between-Molarity-And-Mol...
The answer is Strontium Nitride
Answer: If a hydrogen atom and a helium atom have the same kinetic energy then the wavelength of the hydrogen atom will be roughly equal to the wavelength of the helium atom.
Explanation:
The relation between energy and wavelength is as follows.

This means that energy is inversely proportional to wavelength.
As it is given that energy of a hydrogen atom and a helium atom is same.
Let us assume that
. Hence, relation between their wavelengths will be calculated as follows.
... (1)
... (2)
Equating the equations (1) and (2) as follows.

Thus, we can conclude that if a hydrogen atom and a helium atom have the same kinetic energy then the wavelength of the hydrogen atom will be roughly equal to the wavelength of the helium atom.
A catalyst will ALWAYS increase the reaction rate so C