Helium atom has atomic mass 4 and 2 Proton in its nucleus. how many neutrons does it have?

Thanks for helping Tanu.

You're welcome

ATOMIC MASS=TOTALNO.OF PROTONS+TOTAL NO. OF NEUTRONS
4=2+TOTAL NO. OF NEUTRONS
TOTAL NO. OF NEUTRONS=4 - 2 = 2.

Formula used:
           No. of Protons + No. of Neutrons = (No. of electrons) = Mass number.

Mass number of He = 4
No.of Protons in He = 2

Using the formula,    
              No. of Protons + No. of Neutrons = Mass number.
              No. of Neutrons = Mass number - No.of Protons
              No. of Neutrons = 4-2 = 2

Therefore, No.of Neutrons in Helium atom = 2


TTHIS MAY HELP 

IF IT IS PLZ LIKE