Question

D. Calculate the number of atom in each
of the following (Given : Atomic mass
of I= 127 u).
a. 254 u of iodine (I)
b. 254 g of iodine (I)
(Ans. : 2 atoms, 1.2044 x 1024 atoms)​

Answer 1

Answer :-

( a ) 2 atoms

( b ) $12.046 * 10^{24}$ atoms

Explanation :-

Given :-

Atomic mass of I = 127 u

To Find :-

• No. of atoms in 254 u of Iodine

• No. of atoms in 254 g of Iodine

Solution :-

( a )

No. of atoms = given mass / atomic mass

No. of atoms = 254/127 = 2 atoms.

------------------------

( b )

we know that,

Mass no. = atomic no.

Atomic no. of I = 127 u

-------------------------

Therefore, Molar mass = 127 g

No. of moles = 254/127 = 2

Now,

No. of atoms = no. of moles × Avogadro's no.

No. of atoms = $2 *6.022*10^{24}$

No. of atoms = $12.046*10^{23}$