CHEM 219 MODULES EXAM QUESTIONS
AND CORRECT ANSWERS WITH COMPLETE
SOLUTION |ALREADY GRADED A+ |2026
UPLOAD |100% CORRECT!!
1. What is the chemical formula for the compound formed when Potassium
reacts with Oxygen?
K2O
KO
K2O2
K3O
2. Explain why Selenium (Se) in the +VI oxidation state is considered to react
rapidly. What factors contribute to this reactivity?
It has a full outer electron shell.
It has a high electronegativity.
It is a strong oxidizing agent.
It forms stable compounds.
3. What are the two elements that make up the compound with the formula
InI2?
Indium and Iodine
Iron and Iodine
Indium and Iodide
Iodine and Iodide
,4. Explain the significance of self-dissociation in the context of BF3 and its
implications for Lewis acid behavior.
Self-dissociation indicates that BF3 can act as a Lewis base.
, Self-dissociation shows that BF3 is a strong acid in aqueous
solution.
Self-dissociation reveals that BF3 can form stable complexes with
other Lewis bases.
Self-dissociation demonstrates that BF3 cannot participate in redox
reactions.
5. Explain why the 5s orbital is filled before the 4d orbital in the context of
electron configuration.
Because 5s has a lower energy level than 4d
Because 5s can hold more electrons than 4d
Because 4d is not a valid orbital
Because 5s is closer to the nucleus than 4d
6. Which type of hydrogen bond is generally considered weaker: S—H···O or
O—H···S?
S—H···O
O—H···S
Both are equally strong
Neither can be compared
7. Which of the following is a STRONG acid?
H2O
NH4+
C6H5CO2H
HClO4
HCN
AND CORRECT ANSWERS WITH COMPLETE
SOLUTION |ALREADY GRADED A+ |2026
UPLOAD |100% CORRECT!!
1. What is the chemical formula for the compound formed when Potassium
reacts with Oxygen?
K2O
KO
K2O2
K3O
2. Explain why Selenium (Se) in the +VI oxidation state is considered to react
rapidly. What factors contribute to this reactivity?
It has a full outer electron shell.
It has a high electronegativity.
It is a strong oxidizing agent.
It forms stable compounds.
3. What are the two elements that make up the compound with the formula
InI2?
Indium and Iodine
Iron and Iodine
Indium and Iodide
Iodine and Iodide
,4. Explain the significance of self-dissociation in the context of BF3 and its
implications for Lewis acid behavior.
Self-dissociation indicates that BF3 can act as a Lewis base.
, Self-dissociation shows that BF3 is a strong acid in aqueous
solution.
Self-dissociation reveals that BF3 can form stable complexes with
other Lewis bases.
Self-dissociation demonstrates that BF3 cannot participate in redox
reactions.
5. Explain why the 5s orbital is filled before the 4d orbital in the context of
electron configuration.
Because 5s has a lower energy level than 4d
Because 5s can hold more electrons than 4d
Because 4d is not a valid orbital
Because 5s is closer to the nucleus than 4d
6. Which type of hydrogen bond is generally considered weaker: S—H···O or
O—H···S?
S—H···O
O—H···S
Both are equally strong
Neither can be compared
7. Which of the following is a STRONG acid?
H2O
NH4+
C6H5CO2H
HClO4
HCN
