λ= h/p = h/mv where λ is the wavelength in m (the de Broglie wavelength); h is Planck’s constant = 6.6261 x 10-34 J s-1; m is the mass (in kg) and v is the velocity (m s-1).

http://en.wikipedia.org/wiki/Louis_de_Broglie

So divide your mass of Ne-20 by A (6.023x10^23, and 1000 to get mass of one ion in kg) and put into the de Broglie eqn. good luck!

lets find the frequency of the photons first

f=frequency=?

c=speed of light=3E8 m/s

λ=wavelength=633 nm=6.33E-7 m

f=c/λ

f=3E8/6.33E-7

f=4.739336493E14Hz

now we can find the energy of the photons

E=energy=?

h=planks constant=6.626E-34 J.s

f=4.739336493E14Hz

E=hf

E=6.626E-34 X 4.7393364393E14

E=3.14028436E-19J

ok lets find out how many moles of h20 we have

n=mol=?

M=molar mass=17.9994 g/mol

m=mass=10g

n=m/M

n=10/17.9994

n=.555574075

lets find the energy to melt the ice

E=.555574075 X 6.01 KJ

E=3.339000191 KJ

E=3339.000191 J

lets divide the energy to melt the ice by the energy of one pulse to get the number o pulses required

Npulse=3339.000191/3.14028436E-19J

Npulse=1.063279566E29

so you need a lot of pulses dude

1.06^29

Sounds like physics to me, but at a guess,

calculate the energy of a photon ( E = h / wavelength, 1nm = 10^-9m ), then your pulse energy will be 5x10^18 times more than that. sorry, I dont remember the plank constant value.

find how much energy you need, that is 6.01 kJ per mole.

In 10 g ice, there are 10g / 18g/mol = 0.56 mol H2O to melt.

energy required is 0.56 x 6.01 = 3.34 kJ

now divide the 3.34 kJ needed, by the energy of the pulse, and you will have the minumum number of pulses, must be an integer, so if its a decimal, take it up to the next integer.

Assumption is that 100% of the energy is transferred to the ice, which is nonsense of course, so in reality more pulses would be needed.

This is just some generic information on this subject.

The half-life is the time that it takes for the starting amount to decrease to one-half its original value.

A first-order process is governed by the following relationship:

C = Ae^(-kt)

where

t = time

C = the amount at time t

A = the amount at t=0

k = the rate constant

The units for t and k must be compatible, e.g. sec and sec^-1, respectively.

The half-life and rate constant are related by looking at the case when C = A/2 (half of the original amount is remains):

C = Ae^(-kt)

A/2 = Ae^(-kt)

1/2 = e^(-kt)

ln(1/2) = ln(e^(-kt))

-ln(2) = -kt

t = (ln(2))/k

t½ = (0.693)/k

I recommend that you review the section in your textbook on this subject so that you can see what is expected for an answer to the original question.