calculate the number of moles of Mg in 0.12g(relative mass of Mg=24)

1 mole ----> 24 g

? mole -----> 0.12

moles ( Mg ) = 0.12 / 24

= 0.005 moles of Mg

0.005 moles

To calculate the number of moles of Magnesium (Mg) in 0.12g, you need to use the formula:

moles = mass / molar mass

In this case, the mass of Magnesium (Mg) is given as 0.12g, and the relative atomic mass of Mg is 24 g/mol.

Step-by-step solution:

1. Determine the molar mass:
The molar mass of Magnesium (Mg) is given as 24 g/mol.

2. Convert the mass in grams to moles:
moles = mass / molar mass
= 0.12g / 24 g/mol

3. Calculate the number of moles:
= 0.005 mol

Therefore, there are 0.005 moles of Magnesium (Mg) in 0.12g.