If 38.5 ml of lead (ii) nitrate solution reacts completely with excess sodium iodide to yield 0.0628 g or precipitate, what is the molarity of lead (ii_ ion in the original solution.. i was wondering if any could tell me how to solve this i have been looking over my chapter and can't figure out what i need to do..

The balanced equation that describes the reaction between lead (II) nitrate and sodium iodide to produce lead (II) iodide and sodium nitrate is expressed Pb(NO3)2 + 2NaI → PbI2 + 2NaNO3. All nitrates are soluble so lead (II) iodide is the precipitate. given 0.0628 g PbI2 is equal to 1.3623x10^-4 moles PbI2. This is equal to 1.3623x10^-4 moles also of Pb(NO3)2. Hence the molarity of the solution is 1.3623x10^-4 moles per 0.0385 L or 0.003538 M. 

Ch4 is nonpolar and insoluble in water. since all of the hydrogen atoms are evenly spread around the carbon atom even through the c h bond is polar all the poles cancel each other out.