Which part of an experiment do scientists change the independent or dependent variable?

Which electron configuration represents the electrons of an atom in an excited state? (1) 2-1 (3) 2-8-7 (2) 2-7-4 (4) 2-4

Which two atoms could be the "before'' and ''after'' of an alpha ejection

Which compound has the lowest vapor pressure at 50°C? (1) ethanoic acid (3) propanone (2) ethanol (4) water

An archaeologist discovered some charcoal at an excavation site. He sent the samples to a lab for C-14 dating, knowing that the half-life of C-14 is approximately 5,600 years.

How many Na + ions are in 3.0 moles of Na2O?

Aspirin has a formula c9h8o4. what is the molar mass of aspirin? 1. 95 g 2. 220 g 3. 180 g 4. 325 g

Which of these are ionic compounds?

In a titration 25.0 ml of a. 20 M NaOH solution is used to neutralize 10.0 ml of HCl. Write the equation for this neutralization reaction and calculate the molarity of the acid.

In the fourth century bc Greek scholars rejected Democritus ideas about the atom. This rejection was mostly based on?

An element X has two isotopes. X-15 has 7 protons and 8 neutrons. Determine the atomic number and mass number of the second isotope, which has 10 neutrons in its nucleus. a. atomic number = 8; mass number = 9 b. atomic number = 8; mass number = 17 c.