Which group of elements are the most important for living organisms?/

a. carbon, lead, and tin

b. carbon, nitrogen, and oxygen

c. boron, aluminum, and nitrogen

d. arsenic, antimony, and oxygen

1. Why is it that some combinations of ions do not seem to react while others result in precipitate? 2. For an insoluble compound, how might you prevent formation of precipitate? 3.

What did Newton believe were encoded alchemic recipes?

Is the following a properly written thermochemical equation? 2C8H18 + 25O2 → 16CO2 + 18H2O, ΔH = - 5,471 kJ/mol

Magnesium reacts with oxygen gas to form magnesium oxide. Which of the following represents the balanced chemical equation? Mg + O2 - -> MgO Mg + O2 - -> 2MgO 2Mg + 2O2 - -> 2MgO 2Mg + O2 - -> 2MgO

How many neutrons does an element have if its atomic number is 40 and its mass number is 154

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?