Intensity has no affect on whether or not the photoelectric effect occurs. The determining property is frequency and since frequency and wavelength are inversely proportional, wavelength matters as well. If a frequency of light can't cause the photoelectric effect to happen, no matter what the intensity is, the light can't make it happen.
I hope this helps. Let me know in the comments if anything is unclear.
Currently in this equation, you have 2 hydrogen atoms and 2 oxygen atoms on the left, and then 2 hydrogen atoms and 1 oxygen atom on the right. To balance, you would need to even out the oxygens, so we can first place a 2 in front of H2O to get:
H2 + O2 -> 2H2O
Now, however, you can see that we have too many hydrogen atoms on the right, so to get the final answer, we add a 2 in front of hydrogen on the left:
2H2 + O2 -> 2H2O
I hope this helps!
Answer:
a. 41 mg equals 0.041 grams.
b. 41 mg equals 0.0014462 ounces
c. 41 mg equals 9.039*10⁻⁵ pounds
Explanation:
You know that a slice of Swiss cheese contains 41 mg of sodium.
a. What is this mass in grams?
Knowing that 1 mg = 10⁻³ g, you can apply the following rule of three: if 1 mg equals 10⁻³ g or 0.001 grams, 41 mg will be equivalent to how much mass in g?

mass= 0.041 grams
<u><em>
41 mg equals 0.041 grams.</em></u>
b. What is this mass in ounces?
Knowing that 1 mg = 3.5274 * 10⁻⁵ ounces, you can apply the following rule of three: if 1 mg equals 3.5274 * 10⁻⁵ ounces, 41 mg will be equivalent to how much mass in ounces?

mass= 1.4462*10 ⁻³ ounces= 0.0014462 ounces
<u><em>41 mg equals 0.0014462 ounces</em></u>
c. What is this mass in pounds?
Knowing that 1 mg = 2.20462 * 10⁻⁶ pounds, you can apply the following rule of three: if 1 mg equals 2.20462 * 10⁻⁶ pounds, 41 mg will be equivalent to how much mass in pounds?

mass= 9.039*10⁻⁵ pounds
<u><em>41 mg equals 9.039*10⁻⁵ pounds</em></u>