Answer:
A. No photoelectrons < C. KE = 51 kJ·mol⁻¹ < B. KE = 155 kJ·mol⁻¹
632 nm < 455 nm < 325 nm
Explanation:
The equation for the photoelectric effect is
E = hf = Φ + KE
That is, the energy (hf) of the incident photon is used to eject an electron from the surface of the metal ( the work function, Φ), and anything left over goes into the kinetic energy (KE) of the electron.
1. Calculate the relative energies of the three wavelengths
E = hf
fλ = c or f = c/λ. So,
E = (hc)/λ
The energy is inversely proportional to the wavelength. Thus, the order of increasing energies is
632 nm < 455 nm < 325 nm
2. Assign the radiation to the observations.
Solve the photoelectric equation for KE.
E = Φ + KE
KE = E - Φ
If E < Φ, the light does not have enough energy to eject a photoelectron.
Once E > φ, the greater the value of E, the greater the value of KE.
The order of energies is
A. No photoelectrons < C. KE = 51 kJ·mol⁻¹ < B. KE = 155 kJ·mol⁻¹
632 nm < 455 nm < 325 nm
Answer:
geologic features like craters and mountains
Explanation:
The chemical formula of hydrocortisone valerate is C26H38O6. First, we determine the molar mass of the substance by adding up all the products of the number of atoms and the molar mass of atoms as shown below.
molar mass = 26(12) + 38(1) + 6(16) = 446 g/mol
Since, there are 26 atoms of carbon in each molecule, the mass of carbon in each mole is
mass of carbon = (26)(12) = 312
Obtaining the percent by mass of carbon,
% by mass of carbon = (312/446) x 100 %
= 69.955%
Thus, the percent by mass of carbon in hydrocortisone valerate is approximately 69.96%.
1. Should know the Atomic Number of each element (also equal to the number of protons
2. Should know the Mass number (equals to protons + neutrons)
3. Should know the element's symbol or abbreviation (e.g. C for carbon, Ar for argon etc.)
4. Should know the number of electrons