Chemical Formulas Quiz

Chromium(II) indicates Cr^2+ ion. Nitrate is NO3^- with a -1 charge. To balance the +2 charge of chromium, two nitrate ions are needed, giving the formula Cr(NO3)2. Parentheses are required around NO3 to show two complete nitrate groups.

Ammonium ion is NH4^+ with a +1 charge. Sulfate is SO4^2- with a -2 charge. To balance the charges, two ammonium ions are needed for each sulfate ion, giving (NH4)2SO4. Parentheses are essential around NH4 to indicate two ammonium groups.

Beryllium has a +2 charge (Be^2+). Nitrate is NO3^- with a -1 charge. Two nitrate ions are needed to balance the +2 charge of beryllium, giving Be(NO3)2. Option D is correct.

Strontium has a +2 charge (Sr^2+). Phosphate is PO4^3- with a -3 charge. To balance the charges between +2 and -3, you need 3 strontium ions (total +6) and 2 phosphate ions (total -6), giving Sr3(PO4)2. Option C is correct.

Manganese(IV) indicates Mn^4+ ion. Sulfate is SO4^2- with a -2 charge. To balance the +4 charge of manganese, two sulfate ions are needed, giving Mn(SO4)2. Option B is correct.

Potassium (K) forms a +1 ion, and hydroxide (OH) is a -1 polyatomic ion. They combine in a 1:1 ratio to give KOH. K2OH would imply K2+ which doesn't exist, and K(OH)2 would require a +2 charge.

Nickel(II) means Ni2+. Nitrite is NO2- with a -1 charge. To balance +2 and -1, you need two nitrite ions: Ni(NO2)2. Ni(NO2)3 would give -3, and the formulas for B and C don't balance charges.

Zinc(II) is Zn2+. Nitrite (NO2-) has a -1 charge. Two nitrite ions are needed to balance the +2 charge, giving Zn(NO2)2. Option B would give Zn4+ which doesn't exist, and Zn2NO2 doesn't balance.

Platinum(II) is Pt2+. Carbonate (CO3) has a -2 charge. The 2+ and 2- cancel in a 1:1 ratio, giving PtCO3. Pt2CO3 would be Pt4+, and Pt3(CO3)2 doesn't represent the correct charge balance.

Aluminum is Al3+. Sulfite (SO3) has a -2 charge. To balance +3 and -2, you need the LCM: 2 aluminum atoms (+6 total) and 3 sulfite ions (-6 total), giving Al2(SO3)3. AlSO3 doesn't balance.

Magnesium is Mg2+. Nitrite (NO2-) has a -1 charge. Two nitrite ions are needed to balance +2, giving Mg(NO2)2. Mg3(NO2)2 doesn't balance correctly, and Mg2(NO2)3 would be Mg4+.

Barium (Ba) has a valency of +2, and the sulfate ion (SO4) has a valency of -2. When they combine, the charges balance in a 1:1 ratio, resulting in the chemical formula BaSO4. Other options incorrectly represent the ionic charges or stoichiometry.

Nickel(II) is Ni2+. Sulfite (SO3) has a -2 charge. They balance in a 1:1 ratio, giving NiSO3. Ni2SO3 would require Ni4+, and Ni3(SO3)2 doesn't represent Ni2+ correctly.

Chromium(II) is Cr2+. Sulfate (SO4) has a -2 charge. They cancel in a 1:1 ratio, giving CrSO4. Cr2SO4 would be Cr4+, and Cr(SO4)2 would require Cr4+.

Ammonium is NH4+ with +1 charge. Phosphate is PO4 with -3 charge. To balance +1 and -3, you need 3 ammonium ions and 1 phosphate: (NH4)3PO4. NH4PO4 doesn't balance charges.