<span>Well... first, let's recognize that the chemical formula for chlorodifluoromethane is CHClF2. Count out how many valence electrons there are. C = 4, H = 1, Cl = 7, F (X2) = 14. Total is 26. Let's put C as the central atom, and put the other elements surrounding it. Draw a pair of electrons beach each element and the central atom. Then fill the halogen elements with 3 pairs of electrons each to fill their octets. Count out how many dots you have. There should be 26, making this the correct lewis structure!
Remember, hydrogen doesn't have a full octet, only a maximum of two electrons.</span>
Answer:
2.4 ×10^24 molecules of the herbicide.
Explanation:
We must first obtain the molar mass of the compound as follows;
C3H8NO5P= [3(12) + 8(1) + 14 +5(16) +31] = [36 + 8 + 14 + 80 + 31]= 169 gmol-1
We know that one mole of a compound contains the Avogadro's number of molecules.
Hence;
169 g of the herbicide contains 6.02×10^23 molecules
Therefore 669.1 g of the herbicide contains 669.1 × 6.02×10^23/ 169 = 2.4 ×10^24 molecules of the herbicide.
Answer: 3
Explanation: This is a radioactive decay and all the radioactive process follows first order kinetics.
Equation for the reaction of decay of 
radioisotope follows:
By the stoichiometry of above reaction,
1 mole of 
is produced by 1 mole 
So, 0.17 moles of will be produced by = 
Amount of 
decomposed will be = 0.17 moles
Initial amount of 
will be = Amount decomposed + Amount left = (0.17 + 0.024)moles =0.194 moles
where,
a = amount of reactant left after n-half lives = 0.024
= Initial amount of the reactant = 0.194
n = number of half lives= ?
Putting values in above equation, we get:
Therefore, 3 half lives have passed.
