What is the charge on the iron ion in the compound Fe2O3? Multiple Choice Unequal sharing of electrons in a covalent bond results in a polar bond. True or False True True False In which state of matter are the particles close together and highly organized? Multiple Choice Solid Liquid Gas All of the choices are correct. Atoms with seven valence electrons typically form one covalent bond. True or False True False Phosphorus has 15 valence electrons. True or False True True False False Elements in group 2A form ions with a +2 charge. True or False True False Which of the following compounds is classified as covalent? Multiple Choice KCI LIBI NaBr What is the formula for the lonic compound formed when magnesium and oxygen combine? Multiple Choice Mgo MgO2 M920 Mg202 The molecule below is a polar molecule. H H H-C=C CI True or False True True False False How many lone pairs of electrons are present in the Lewis structure of ammonia, NH3? Multiple Choice o o o o
The Correct Answer and Explanation is:
1. What is the charge on the iron ion in Fe₂O₃?
Correct Answer: +3
Explanation:
Fe₂O₃ contains 2 iron (Fe) atoms and 3 oxygen (O) atoms. Oxygen typically forms a -2 ion, so 3 oxygen atoms contribute a total charge of -6. To balance this, the 2 iron atoms must contribute +6, meaning each Fe must be +3.
2. Unequal sharing of electrons in a covalent bond results in a polar bond.
Correct Answer: True
Explanation:
A polar covalent bond occurs when atoms share electrons unequally due to differences in electronegativity. This leads to a partial positive and negative charge on each atom, creating a dipole. Water (H₂O) is a classic example.
3. In which state of matter are the particles close together and highly organized?
Correct Answer: Solid
Explanation:
In solids, particles are tightly packed in a fixed, orderly arrangement. This contrasts with liquids (close but disordered) and gases (far apart and random).
4. Atoms with seven valence electrons typically form one covalent bond.
Correct Answer: True
Explanation:
Atoms like chlorine (Cl) have 7 valence electrons and need 1 more to complete the octet, hence they usually form one single covalent bond.
5. Phosphorus has 15 valence electrons.
Correct Answer: False
Explanation:
Phosphorus has 15 total electrons, but only 5 valence electrons because it’s in Group 5A of the periodic table.
6. Elements in Group 2A form ions with a +2 charge.
Correct Answer: True
Explanation:
Group 2A elements like Mg and Ca lose their two valence electrons to achieve a full shell, forming +2 cations.
7. Which compound is covalent?
Correct Answer: None listed; all are ionic.
Explanation:
KCl, LiBr, and NaBr are formed between metals and nonmetals, making them ionic compounds, not covalent.
8. Formula for compound formed by magnesium and oxygen?
Correct Answer: MgO
Explanation:
Magnesium (Mg²⁺) and oxygen (O²⁻) combine in a 1:1 ratio to form MgO. Charges cancel out, making it neutral.
9. Is the molecule H–C=C–Cl polar?
Correct Answer: True
Explanation:
Chlorine is much more electronegative than hydrogen and carbon, causing an unequal electron distribution and making the molecule polar.
10. Lone pairs in NH₃ (ammonia)?
Correct Answer: 1
Explanation:
Ammonia has 3 bonded pairs (with hydrogen) and 1 lone pair on nitrogen, totaling 4 electron domains around nitrogen
.