Question

the end of the sentence is made by dot with lead pencil and its mass is 10^-4 gm.find the number of carbon atoms in the dot

Answer 1

Answer:

Explanation:

Each mole of any element has Avogadro number of atoms

i.e in case of carbon 12 gm will have 6.022*10^23 atoms

hence 1 gm have=0.5*10^23

10^-4 will have=0.5*10^19 or 5 * 10^18 Atoms

Answer 2

Given mass of dot (containing carbon) = 10^(-4) g.

Now, atomic mass of Carbon is 12 g/mol.

Now, let's find out the number of moles :

$moles = \dfrac{given \: mass}{atomic \: mass}$

$\implies moles = \dfrac{ {10}^{ - 4} }{12}$

$\implies moles = 0.83 \times {10}^{ - 5}$

Now, number of atoms will be :

$\implies atoms = moles \times 6.023 \times {10}^{23}$

$\implies atoms =0.83 \times {10}^{ - 5} \times 6.023 \times {10}^{23}$

$\implies atoms =5 \times {10}^{ 18}$

So, 5 × 10¹⁸ atoms of Carbon are present in the dot.