What do all atoms in one element have in common?

What can be said about the number of electrons atoms of one element can have?

What structural units make up metallic solids? O A. Molecules O B. Nonmetal atoms O c. lons O D. Metal atoms

Suppose you have 50 grams of a radioactive isotope with a half-life of 2 years. How much of the isotope will you have after 4 years? A) 50 B) 25 C) 12.5

Which reactions are oxidation-reduction reactions? 1. FeS (s) + 2HCl (aq) → H2S (g) + FeCl2 (g) 2. AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 3. 2C3H6 (g) + 9O2 (g) → 6CO2 (g) + 6H2O (g) 4. Fe2O3 (s) + 3CO (g) → 2Fe (l) + 3CO2 (g)

4. A calorimeter contains 500 g of water at 25°C. You place a hand warmer containing 200 g of liquid sodium acetate inside the calorimeter. When the sodium acetate finishes crystallizing, the temperature of the water inside the calorimeter is 39.4°C.

Which one of the following is a vestigial structure? 1. Heart 2. Appendix 3. Right leg 4. liver

Is a molecule positive or negative?

A friend tells you, because composition does not change during a physical changes, the appearance of a substance does not change. is your friend correct? explain why.

In which direction dose the sun appear to move across the sky

Which is the SI unit for pressure? Pa Torr psi inHg

Write a neutralization reaction for each acid and base pair. a. HI (aq) and NaOH (aq) b. HBr (aq) and KOH (aq) c. HNO3 (aq) and Ba (OH) 2 (aq) d. HClO4 (aq) and Sr (OH) 2 (aq)