Question

how many total atoms are present in 1.8g of glucose​

Answer 1

Formula of Glucose = C6H12O6
Weight = 1.8 g
Molecular mass = 12*6 + 1*12 + 16*6 = 180

Number of atoms = 1.8/180 * 6.023 * 10^23 * 24
                             = 1.45 * 10^23

Answer 2

Given:  

$\begin{array}{l}{\text { Mass of glucose }=1.8 \mathrm{g}} \\ {\text { Molar mass of the glucose = } 180 \frac{g}{m o l}} \\ {\text { Number of moles of glucose }=\frac{\text { Mass }}{\text { Molar mass }}} \\ {=\frac{1.8}{180}=0.01 \text { moles }} \\ {\text { The chemical formula of glucose }=\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}}\end{array}$

$\begin{array}{l}{\text { Moles of } \mathrm{C} \text { atom }=0.01 \times 6=0.06 \text { moles of } \mathrm{C}} \\ {\text { Moles of } \mathrm{H} \text { atoms } 0.01 \times 12=0.12 \text { moles of } \mathrm{C}} \\ {\text { Moles of } \mathrm{O}=0.01 \times 6=0.06 \text { moles of } \mathrm{O}}\end{array}$

$\begin{array}{l}{\text { Hence } C \text { atoms }=0.06 \times 6.022 \times 10^{23} \text { atoms }} \\ {=0.36 \times 10^{23} \text { atoms }} \\ {\text { O atoms }=0.06 \times 6.022 \times 10^{23} \text { atoms }} \\ {=0.36 \times 10^{23} \text { atoms }} \\ {\text { H atoms }=0.12 \times 6.022 \times 10^{23} \text { atoms }} \\ {=0.72 \times 10^{23} \text { atoms. }}\end{array}$

$\begin{array}{l}{\text { Hence the total atoms present in } \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} \text { is, }} \\ {\quad=\left(0.36 \times 10^{23}\right)+\left(0.36 \times 10^{23}\right)+\left(0.72 \times 10^{23}\right.} \\ {=1.44 \times 10^{23} \text { atoms. }}\end{array}$