What is a mole? list everything you know about the mole.
how many atoms are present in 3.8 moles of sodium hydroxide, naoh?
calculate the molar mass for ca(oh)2.

1. A mole is the amount which contains as many elementary particles as there are atoms in 12 grams of carbon-12. It is also the unit used in measuring the amount of matter. A mole also refers to the Avogadro's number of particles present in any substance.

2. 1mole of NaOH contains 6.02x10^23 atoms.

Therefore, 3.8 moles of NaOH will contain = 3.8 x 6.02x10^23 = 2.288 x 10^24 atoms

3. Molar Mass of Ca(OH)2 = 40 + 2(16+1) = 40 2(17) = 40 + 34 = 74g/mol

Explanation:

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.