Fluoride, a naturally occurring mineral, helps prevent cavities and can even reverse the earliest stages of tooth damage. Because of its benefits for teeth, fluoride is added to many public water supplies. It's also a common ingredient in toothpaste and mouth rinses
Copper + sulfur create copper sulfide.
It's a lengthy process to find the empirical formula:
Sulfur:
Copper:
S:Cu => 
=> 
=> 
The empirical formula would just be 
Answer:
Forensic drug chemists analyze samples of unknown materials including powders, liquids and stains to determine the chemical identity or characteristics of the compounds that make up the sample. samples submitted as evidence in a drug-related case can contain one compound or a mixture of many compounds.
Answer:
3
Explanation:
the half life of a radioactive isotope is the amount of time one half of the isotope takes to decay
after 5 minutes the mass will be 24
after 10 minutes the mass will be 12
after 15 minutes the mass will be 6
after 20 minutes the mass will be 3
Answer:
Option c is correct
Explanation:
The interstitial alloy elements occupy the free spaces in the metal structure and improve the symmetry of the crystalline network, for this reason this type of elements increases the hardness of the metal.
Vitreous metals are called that because they are formed by high cooling rates and form amorphous structures such as glass, such structures contain packaging of atoms of different sizes, which decreases the free spaces in the metal structure and this increases their hardness.
In option d, the work at low temperatures causes the vibrations of the atoms to decrease and compact, this makes many metals brittle but in general increases their hardness.
Option c is correct because in annealing the metal is heated to the austenization temperature, that is, the temperature at which a structural change occurs, which destroys its crystalline network and then slowly cools to maintain this structure change and by causing this disorder, the spaces between the atoms increase and the hardness of the metal decreases.
