DDT was one of the first chemicals in widespread use as a pesticide.
<span><span>Food supplies: USDA found DDT breakdown products in 60% of heavy cream samples, 42% of kale greens, 28% of carrots and lower percentages of many other foods.</span><span>Body burden: DDT breakdown products were found in the blood of 99% of the people tested by CDC.</span><span>Health impacts: Girls exposed to DDT before puberty are 5 times more likely to develop breast cancer in middle age, according to the President’s Cancer Panel.</span></span>
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:
The partial pressure of the other gases is 0.009 atm
Explanation:
Step 1: Data given
Air is about 78.0% nitrogen molecules and 21.0% oxygen molecules and 1% of other gases.
The atmospheric pressure = 0.90 atm
Step 2: Calculate mol fraction
If wehave 100 moles of air, 78 moles will be nitrogen,
21 moles will be oxygen, and 1 mol will be other gases.
Mol fraction = 1/100 = 0.01
Step 3: Calculate the partial pressure of the other gases
Pgas = Xgas * Ptotal
⇒ Pgas = the partial pressure = ?
⇒ Xgas = the mol fraction of the gas = 0.01
⇒Ptotal = the total pressure of the pressure = 0.90 atm
Pgas = 0.01 * 0.90 atm
Pgas = 0.009 atm
The partial pressure of the other gases is 0.009 atm
Explanation:
A reaction quotient is defined as the ratio of concentration of products over reactants raised to the power of their stoichiometric coefficients.
A reaction quotient is denoted by the symbol Q.
For example, 
The reaction quotient for this reaction is as follows.
Q = ![\frac{[Fe^{2+}]^{2}[Zn^{2+}]}{[Fe^{3+}]^{2}}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BFe%5E%7B2%2B%7D%5D%5E%7B2%7D%5BZn%5E%7B2%2B%7D%5D%7D%7B%5BFe%5E%7B3%2B%7D%5D%5E%7B2%7D%7D)
[Zn] will be equal to 1 as it is present in solid state. Therefore, we don't need to write it in the reaction quotient expression.
