Ответ:

Объяснение:

Mr(MgBr2) = 24 + 80 * 2 = 184 г/моль

w(Mg) = n * Ar / Mr * 100% = 24/184  * 100% = 13,04%

w(Br) = n * Ar / Mr * 100% = 2 * 80/184  * 100% =86,96%

Mr(K2CO3) = 39 * 2+ 12 + 16 * 3 = 138 г/моль

w(Mg) = n * Ar / Mr * 100% = 2 * 39/138  * 100% = 56,5%

w(С) = n * Ar / Mr * 100% = 12/138  * 100% = 8,7%

w(О) = n * Ar / Mr * 100% = 3 * 16/138  * 100% = 34,8%