Question

indique o nox do Cr nos sais K2Cr2O7 e CaCrO4

Answer 1

 +1        -2
$K_{2} Cr_{2} O_{7}$

2.1 + 2 Cr + 7 (-2) = 0
2 + 2Cr - 14 = 0
2 Cr = 14 - 2
2 Cr = 12
Cr =+6
      
+2        -2
$CaCrO_{4}$
2 + Cr + 4 (-2) =0
2 + Cr -8 = 0
Cr = 8 - 2 
Cr = +6