Question

If the mass of 0.25 moles of an element X is 2.25 g, the mass of one atom of X is about :
(A) 1.5 x 10-24 g (B) 2.5 x 10-23 g (C) 1.5 x 10-23 g (D) 2.5 x 10-24 g​

Answer 1

Answer:

option C

Explanation:

${no. \: of \: moles \: = } \frac{given \: mass}{total \: mass \: of \: the \: element}$

Given;

no. of moles=0.25

given mass=2.25g

total mass of element=?

0.25=2.25/x

x=2.25/0.25

x= 9 g/mol

every 1 mol of substance contains 6.023×10^23 atoms

So for 1 atom , mass is 9/6.023×10^23 g

so it is 1.5×10^-23 g or option C