Question

what is the charge of the nickel ion in the compound nis?
options: +3, +4, +1, +2
write the correct name for the compound pbcl₄.
your answer
what is the correct chemical formula for the compound copper(ii) hydroxide?
your answer
the name nickel(ii) carbonate tells us the nickel ion has a charge of +2.
options: false, true
which formula is correct for chromium(iii) oxide

Explanation:

First Question (Charge of Nickel ion in NiS)

Step1: Recall ion charges in compounds

Sulfide ion (\(S^{2-}\)) has a charge of -2. In a neutral compound, total positive charge = total negative charge. Let nickel's charge be \(x\). For NiS, \(x + (-2) = 0\).

Step2: Solve for nickel's charge

From \(x - 2 = 0\), we get \(x = +2\).

Step1: Identify ion charges

Lead (Pb) can have multiple charges. In \(PbCl_4\), chloride (\(Cl^-\)) has -1 charge. Let Pb's charge be \(x\). Then \(x + 4(-1) = 0 \implies x = +4\).

Step2: Name the compound

Use Roman numerals for lead's charge. So it's Lead(IV) chloride.

Step1: Identify ions

Copper(II) ion is \(Cu^{2+}\), hydroxide ion is \(OH^-\).

Step2: Balance charges

To balance \(2+\) and \(1-\), we need 2 \(OH^-\) for 1 \(Cu^{2+}\). So formula is \(Cu(OH)_2\).

Answer:

+2 (corresponding to the option with +2)

Second Question (Name of \(PbCl_4\))