Which of the following is an example of a double replacement reaction?

(a) 3Fe + 2O2 Fe3O4

(b) BaCl2 + K2CO3 BaCO3 + 2KCl

(c) NiCO3 NiO + CO2

(d) Cl2 + 2NaBr 2NaCl + Br2

What was the old percentages of copper to zinc before 1983?

How does the number of protons compare to the number of electrons in a cation?

The air all around us is a mixture of gasses containing nitrogen, oxygen, carbon dioxide, argon and water vapor. If the partial pressure of nitrogen is 1.

Which descriptions are true of carbonated drinks? Select all that apply. A. They are solutions. B. They are heterogeneous mixtures. C. They are depositions. D. They are homogeneous mixtures. E. They are suspensions.

Five of the six treatments in this experiment use a vinegar solution. Why is it important to use a water solution at the beginning of the experiment for Sample A instead of just starting with Sample B?

A fog over a lake. what two changes of state must occur to produce the fog? do the water molecules absorb or release energy during these changes of state? what happens to the motion of the water molecules as a result?

Limes have a [H3O+] of 1.3 x 10-2 mol/L. Their pOH is

The human body is 0.0040% iron. How many milligrams of iron does a 165 pound person contain?

Which of the following is the correct Lewis structure for ammonia (NH3) ? Note: Hydrogen and nitrogen have one and five valence electrons respectively.

Which of the following statements is true? A. Particles of a solid have a very orderly, three dimensional arrangement and do not move B. Particles of a liquid change shape and volume C.