7. An element found in period 4 would have how many energy levels/shells?

Using the bohr model describe the changes in electrons energy and electron location when an atom changes from the ground state to an excited state.

Can someone best explain why a washing machine represents an open system

The primary product of the combustion of sulfur is:

To slow down a chemical reaction what should you add

A 12.34 ml solution with an unknown salt concentration had a mass of 10.25g. when the water was evaporated from the solution 4.78 g of NaCl remained. Calculate the mass-mass percent NaCl concentration in the solution.

Should a bartender use ice and scoop directly from ice machine or use an ice holding device and scoop to make drinks and refill drinks from

What classification should this reaction have? 4Al + 3O2 → 2Al2O3

If you start with 100 grams of a radionuclide, how much will you have after two half-lives have passed?

Identify the spectator ions in the following complete ionic equation. 2k (aq) s2 - (aq) pb2 (aq) 2no-3 (aq) →pbs (s) 2k (aq) 2no-3 (aq) express your answers as ions separated by a comma.

4. A bird left its post and flew in a triangular path. It flew 21 yards south, 72 yards east and 75 yards diagonally to end back at the post. Is it a right triangle?