Cr <span>1s</span>2 <span>2s</span>2 <span>2p</span>6 <span>3s</span>2 <span>3p</span>6 <span>4s</span>1 <span>3d</span>5
3BaO + 2H3PO4 = Ba3(PO4)2 + 3H2O
Ответ: 9