How many hydrogen atoms are present in a 2.65 gram sample of hydrazine (N2H4)?

4.95×10^22 atoms of hydrogen.

Explanation:

Now, we must remember that the number of elementary entities in one mole of a substance (atoms, molecules, ions,etc) is given by the Avogadro's number. Avogadro's number is numerically equal to 6.02×10^23.

We must first find the number of moles of hydrazine corresponding to 2.65 g

We find that from;

Number of moles= mass of hydrazine given/ molar mass of hydrazine

Molar mass of hydrazine= 32.0452 g/mol

Number of moles of hydrazine= 2.65/32.0452 g/mol= 0.0823 moles

If 1 mole of hydrazine contains 6.02×10^23 hydrogen atoms

0.0823 moles of hydrazine will contain 0.0823 moles × 6.02×10^23 = 4.95×10^22 atoms of hydrogen.

i think its 5049.

i hope this !