When two substances are mixed and light is produced is it a chemical or physical change?

What is the number of valence electrons in a nitrogen atom in the ground state

Calculate how much gasoline and money could be saved if the automobile's fuel efficiency were increased by 25%. Gasoline = 25 gallons per week Money = $2 per gallon ($50 total)

Cyclohexane + culi what is the major organic product

If an object is weightless can it have mass

In a chemical reaction, atoms are created or destroyed. true or false user: heat, gas production, and color change can all be evidence of chemical change. true or false

Calculate Zeff for the 4s electron in a copper Cu

And the cell potential is - 54.0 mv (inside negative), calculate the maximum ration of

What is the final ph of a solution created by adding 12 ml of 0.5 m hcl to 300 ml of 100 mm formate if the pka for formic acid is 3.78?

Imagine that an uncharged pith ball is brought into the electrostatic field of a charged rod. The side of the pith ball closest to the negatively charged end of the rod will

When forces attracting solvent particles to each other are broken, what is provided for a solution? energy for the solute to precipitate space for the solute in the solvent inertia for the solute to move into the solvent nothing is provided