JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ Sample Paper Topic Test - Some Basic Concepts of Chemistry

What is the atomic weight of an element X for which a sample containing \[1.58\times {{10}^{22}}\] atoms weigh 1.05 g?

A) 28 g

B) 20 g

C) 40 g

D) 23 g

Correct Answer: C

Solution :

[c] We know that, one mole of an element \[=6.02\times {{10}^{23}}\] atoms

= Atomic weight of the element

Now, \[1.58\times {{10}^{22}}\] atoms weigh 1.05 g

\[\therefore \] \[6.02\times {{10}^{23}}\] atoms weigh

\[=\frac{(1.05\times 6.02\times {{10}^{23}})}{1.58\times {{10}^{22}}}\]

= 40 g

Atomic weight of \[X=40g\]