Question

The mass of an atom of element a is 3.33×10^-25 . find it atomic weight

Answer 1

Atomic weight of element is 0.20 grams.

GIVEN:

The molar mass of atom = 3.33 × 10⁻²⁵grams

TO FIND

Atomic weight of an element

SOLUTION:

Mass of 1 atom = 3.33 × 10⁻²⁵

we know that, atomic weight and molar mass of elements is same

In 1 mole of atom = 6.022 × 10²³ atoms

Mass of 1 mole atoms = 3.33 × 10⁻²⁵ × 6.022× 10²³

= 20.05 × 10⁻²

= 0.20 grams

Hence, Atomic weight of element is 0.20 grams.

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Answer 2

Correct question:

If the mass of one atom is 3.32 × 10⁻²³ g, then calculate the atomic weight.

Answer:

The atomic weight is 20 g.

Explanation:

Given,

The mass of an atom 'a' is 3.32 × 10⁻²³ g.

To find,

The atomic weight of the atom 'a'.

Calculation,

We know that the weight of 1 proton or 1 neutron is 1.67 × 10⁻²⁴ g.

And if we are able to find how many neutrons and protons are present in an atom, then we will be in a position to tell the atomic weight of an atom because protons and neutrons only devote to the mass of an atom.

And also we know that 1 atomic mass unit is nothing but the weight of 1 proton or neutron.

So, if the mass of one proton or neutron of an atom 'a' is 1.67 × 10⁻²⁴ g, then 'n' no. of protons or neutrons will have 3.32 × 10⁻²³ g.

$\implies n = \frac{3.33 \times 10^{-23}}{1.67 \times 10^{-24}}$

n = 19.8 ≈ 20

Hence, if 20 nucleons are present then the atomic weight is 20 g.

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