Explanation:
PbI2 is the precipitate.................
Explanation:
1) refine the specimen into fine powder 2) place the smallest amount you can see in the capillary tube 3) set the voltage to increase exponentially to 200 below the predicted temperature, then adjust so that the temperature rises to 20 per minute 4) report the temperature at which the liquid first appears and the temperature at which the last crystal disappears.
The mass of piece of sterling silver jewelry is 33.24 g. It contains 92.5% silver Ag by mass. Since, sterling silver is an alloy of Ag-Cu thus, percentage of Cu will be:
% Cu=100-92.5=7.5%
Thus, mass of copper will be:
Molar mass of Cu is 63.546 g/mol, thus, number of moles of Cu can be calculated as follows:
Here, m is mass and M is molar mass.
Putting the values,
Now, in 1 mole of Cu there are 
thus, in 0.03923 mol, number of Cu atoms will be:
Thus, number of atoms of Cu will be
.
Answer:
B. One element and one compound
Explanation:
O2 is a diatomic element: "are pure elements that form molecules consisting of two atoms bonded together"
*there are 7 types of diatomic elements
and...
C8H12O6 is a compound
Chemical Compound can be described as "a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds"
Compound is a pure substance where atoms of two or more elements are chemically bonded togather
