Question

atomic radii of the elements of the second period are given below:
period 2 elements :B Be O N Li C
Atomic radius (pm) :88 111 66 74 152 77

Answer 1

Answer:

For Helium,

Number of atoms=Number of moles ×6.022×10  

23

 

No of Moles =  

6.022×10  

23

 

12.044×10  

23

 

​  

 = 2.

Now, atomic mass of He=4

Weight = 2×4 = 8 g

Explanation: