The molar mass of magnesium (mg) is 24.30 g/mol. there are 6.02 1023 atoms in 1 mol.

how many atoms are present in 48.60 g of mg?
3.32 10^–24 atoms
1.96 10^–21 atoms
1.20 10^24 atoms
7.11 10^26 atoms

In 48.6 grams of Mg there are

Explanation:

A simple way to obtain the amount of atoms is by means of rules of three:

On one hand, you know the molar mass of Mg: 24.3 g / mol.  This means that in one mole of Mg there are 24.3 grams. But you have 48.6 grams, so you must determine how many moles are that amount of mass. As mentioned earlier, you can calculate it using a rule of three: if there are 24.3 grams in a mole, how many moles are 48.6 grams?

moles of Mg=2 moles

On the other hand, you know that in one mole of Mg there are atoms. And you know that 48.6 grams are 2 moles. Then, you can reapply a simple rule of three: if in one mole there are atoms, how many atoms are in 2 moles?

number of atoms=

Finally, you can say that in 48.6 grams of Mg, which are 2 moles, there are

what is the question here. i think you messed up.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.