Question
Luis made a table of some of the elements and the charges of their ions from period 4.
Element Charge
K +2
Ca +2
Cr +2 or +3
Se −2
Br −1
According to information in the periodic table, what mistake did Luis make in his table?
A. The −2 charge for Se is incorrect, because Se is in group 17 which have charges of −1
when they form ions.
B. The +2 charge for K is incorrect, because K is in group 1 which have charges of +1
when they form ions.
Question: 15
C. The +2 charge for Cr is incorrect, because Cr is in group 1 which have charges of +1
when they form ions.
D. The −1 charge for Br is incorrect, because Br is in group 1 which have charges of −2
when they form ions
Element Charge
K +2
Ca +2
Cr +2 or +3
Se −2
Br −1
According to information in the periodic table, what mistake did Luis make in his table?
A. The −2 charge for Se is incorrect, because Se is in group 17 which have charges of −1
when they form ions.
B. The +2 charge for K is incorrect, because K is in group 1 which have charges of +1
when they form ions.
Question: 15
C. The +2 charge for Cr is incorrect, because Cr is in group 1 which have charges of +1
when they form ions.
D. The −1 charge for Br is incorrect, because Br is in group 1 which have charges of −2
when they form ions
Answers
GPT-5 mini
Answer: B.
Potassium (K) is in group 1 and forms +1 ions, so K +2 is incorrect. The others are consistent: Ca (group 2) is +2, Cr (a transition metal) commonly forms +2 or +3, Se (group 16) is −2, and Br (group 17) is −1.
Potassium (K) is in group 1 and forms +1 ions, so K +2 is incorrect. The others are consistent: Ca (group 2) is +2, Cr (a transition metal) commonly forms +2 or +3, Se (group 16) is −2, and Br (group 17) is −1.