Question

some metals can form ions of different charges in different compounds. deduce the charge of the cr ion in the compound cr(no₃)₃. options: 1+, 3+, 2+, 1-

Explanation:

Step1: Recall nitrate ion charge

Nitrate ion ($\ce{NO3^-}$) has a charge of $-1$.

Step2: Let Cr charge be \( x \), set equation

In $\ce{Cr(NO3)3}$, there is 1 Cr ion and 3 nitrate ions. The compound is neutral, so total positive charge = total negative charge.
Equation: \( x + 3\times(-1) = 0 \)

Step3: Solve for \( x \)

\( x - 3 = 0 \) → \( x = 3 \). So Cr ion charge is \( 3+ \).

Answer:

3+ (corresponding to the option "3+")