Объяснение:

Mr[K2SiO3] = Ar[K] * 2 + Ar[Si] + Ar[O] * 3 = 39 * 2 + 28+ 16* 3 = 154г/моль

w(K)=n•Ar[K] /Mr[K2SiO3] •100%=(2•39/154)•100%=50.65%

w(Si)=n•Ar[Si] /Mr[K2SiO3] •100%=(28/154)•100%=18.18%

w(O)=n•Ar[O] /Mr[K2SiO3] •100%=(3•16/154)•100%=31.17%