Is this museum__the one___they visited yesterday?
正常语序是：this museum is the one （that）they visited yesterday.
the one是表语that they visited yesterday是定语从句用来修饰the one,that在从句中做宾语,可以省略,此处不能用which来引导定语从句
Is this the museum which/that they visited yesterday?
正常语序是this is the museum which/that they visited yesterday
the museum 是表语,which/that they visited yesterday是定语从句,which、that在从句中做宾语,也可以省略.