Best Answer
1 mole of a substance contains 6.022x10^23 "units" of that substance.
So 0.187 mol of Na+ is 1.13x10^23 ions (6.022x10^23 x 0.187).
Resistance of a material being scratched in known as: Hardness
For this question, assume that you have 1 compound. This compound is divided in half once, so you are left with 0.5. That 0.5 that remains is divided in half again, this is the second half-life, and you are left with 0.25. The final half life involves dividing 0.25 in half, which means you are left with 0.125. For the answer to make sense, you need to know your conversions between decimals and fractions. To make it simple, if you have 0.125 and you times it by 8, you are left with your initial value of 1. Therefore, after three half-lives, you are left with 1/8th of the compound.
Answer:
Mass: 981.0 g
Density: 5.61 g/cm^3
Hardness: = 2.5 - 3
Unknown material: Chalcocite
Explanation:
They are eaten by Tertiary consumers
