The number of grams in 2.56 x 1025 molecules of HCl are

1569.5g

Explanation:

Given parameters:

Number of molecules   = 2.56 x 10²⁵

Unknown:

Mass of HCl  = ?

Solution:

To solve this problem, let us find the number of moles first;

      Number of moles  =  

 So,

    Number of moles  =   = 0.43 x 10²  = 43mol

Now;

 Mass of HCl  = number  of moles x molar mass

           Molar mass of HCl   = 1 + 35.5 = 36.5g/mol

   Mass of HCl  = 43 x 36.5  = 1569.5g