4.0 g of sodium hydroxide NaOH was dissolved in sufficient water to make up 125 mL of solution. A) Find the concentration of the solution.

B) What mass of sodium hydroxide could be obtained by heating a 20 mL sample of this solution to dryness?

C) If 30 mL of the solution were mixed with sufficient water to produce 480 mL of a more dilute solution, what would be the concentration of the dilute solution?

D) If 200 mL of the more dilute solution were then mixed with 100 mL of the more concentrated solution, what would be the concentration of the mixed solution?

What is the percentage composition of carbon in the compound ch4

Americium-241 undergoes fission to produce three neutrons per fission event. if a neutron-absorbing material is mixed in with this sample so that the rate of neutron production drops down to 1.8 neutrons per fission event, which will be effective at achieving a critical mass? check all that apply. remove a deflective shield surrounding the sample. remove absorbent material mixed in with the sample. compress the sample of americium-241.

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)