First, we have to calculate the number of moles of 1.50 grams of glucose, using its molar mass which is 180 g/mol (you can calculate it using the periodic table and doing the algebraic sum):
[tex]1.5gC_6H_{12}O_6\cdot\frac{1\text{ mol }C_6H_{12}O_6}{180\text{ g }C_6H_{12}O_6}=0.0083\text{ moles }C_6H_{12}O_6[/tex]And now, let's use Avogadro's number, which is 6.022 x 10^(23) /mol. This number is telling us that there are 6.022 x 10^(23) atoms or molecules in 1 mol. The number of atoms of glucose is:
[tex]0.0083\text{ moles }C_6H_{12}O_6\cdot\frac{6.022\cdot10^{23}molecules\text{ }C_6H_{12}O_6}{1\text{ mol }C_6H_{12}O_6}=5.0\cdot10^{21}\text{molecules }C_6H_{12}O_6.[/tex]To find the number of atoms in C, you can see that there are 6 atoms of this in glucose, so we're going to calculate:
[tex]5.0\cdot10^{21}\text{molecules }C_6H_{12}O_6\cdot\frac{6\text{ atoms C}}{1\text{ molecule }C_6H_{12}O_6}=3.0\cdot10^{22}\text{atoms C.}[/tex]For hydrogen, we have 12 atoms of this in glucose:
[tex]5.0\cdot10^{21}\text{molecules }C_6H_{12}O_6\cdot\frac{12\text{ atoms H}}{1\text{ molecule }C_6H_{12}O_6}=6.0\cdot10^{22}ato\text{ms H.}[/tex]And finally, we have 6 atoms of oxygen in glucose:
[tex]5.0\cdot10^{21}\text{molecules }C_6H_{12}O_6\cdot\frac{6\text{ atoms O}}{1\text{ molecule }C_6H_{12}O_6}=3.0\cdot10^{22}\text{atoms O.}[/tex]The answer is that we have 3.0 x 10^(22) atoms of oxygen (O), 3.0 x 10^(22) atoms of carbon (C), and 6 x 10^(22) atoms of hydrogen (H).
