<span>Strong nuclear forces hold the nucleus of an atom together. Weak nuclear forces are involved when certain types of atoms break down.</span>
The energy required by the excitation of the line is:
ΔE = hν = hc / λ
where:
ΔE = energy difference
h = Planck constant
ν = line frequency
c = speed of light
λ = line wavelength
The energy difference must be supplied by the electron, supposing it transfers all its kinetic energy to excite the line:

Therefore,

And solving for v we get:

Plugging in numbers (after trasforing into the correct SI units of measurement):

=9.4 · 10⁵ m/s
Hence, the electron must have a speed of
9.4 · 10<span>
⁵ m/s in order to excite the <span>492nm</span> line.</span>
Upwards, heat automatically goes up and cool air goes down
Answer:
6.97 grams
Explanation:
T = m × Kf
m ( molality) = T/Kf
T = -15°C = -15+273 = 258 K
Kf = 1.86°C/m = 1.86°C/m × 1K/1°C = 1.86 K/m
Molality = 258/1.86 = 138.71 mol/kg
Mass of ethylene glycol = molality×mass of water in kilograms×molecular weight of ethylene glycol
1 mole of water = 22.4 L
1 L of water = 1/22.4 = 0.045 mol
Mass of water = 0.045 mol × 18g/mol = 0.81 g = 0.81/1000 = 8.1×10^-4 kg
Mass of ethylene glycol = 138.71×8.1×10^-4×62 = 6.97 grams