Which of these is an indication that a chemical reaction has occurred? A. Melting of a substance B. Boiling of a substance C. Formation of a gas D. Freezing of a substance

When one form of energy is converted to another form in any physical or chemical change, energy input alwasy equals energy output?

Briefly explain whether the following procedural error would result in either an incorrectly high or incorrectly low calculated percent recovery of Copper

Which best describes what happens when a neutral atom becomes a positive ion? O A. The remaining electrons spread farther out. O B. The excess protons pull harder on the fewer electrons O C. The remaining electrons are more easily lost. O D.

Which best explains what happens when an electron moves from an excited state to the ground state? The electron absorbs energy as it moves to a lower energy level. The electron absorbs energy as it moves to a higher energy level.

If a 2.8 mole sample of gas initially occupies 54 L at 3.8 atm, what is its temperature in K? n= R= T=

What do Lewis dot structures show?

300 grams of a compound which contains only carbon, hydrogen and oxygen is analyzed and found to contain the exact same percentage of carbon as it has oxygen. The percentage of hydrogen is known to be 5.98823%.

What element has the electron arrangement 2,8,4?

If you get pregnant in Dec how long will it take for u to get to second trimester

Name the following compound HClO