Which molecule has a central atom with no lone pairs?

Here are the solutions to the chemistry quiz questions:

2. Which molecule has a central atom with no lone pairs?

• A) $\text{NH}_3$: Nitrogen has one lone pair.
• B) $\text{H}_2\text{O}$: Oxygen has two lone pairs.
• C) $\text{CH}_4$: Carbon has no lone pairs.
• D) $\text{SO}_2$: Sulfur has one lone pair.
• The correct option is C.

$$\boxed{\text{C}}$$

23. Resonance in nitrate ion ($\text{NO}_3^-$) results in:

• The nitrate ion has one double bond and two single bonds that are delocalized through resonance, resulting in three equivalent bonds.
• The correct option is B.

$$\boxed{\text{B}}$$

24. Molecular geometry of $\text{CH}_4$ is:

• Methane ($\text{CH}_4$) has a central carbon atom bonded to four hydrogen atoms with no lone pairs, leading to a tetrahedral geometry.
• The correct option is A.

$$\boxed{\text{A}}$$

25. Molecular geometry of $\text{NH}_3$ is:

• Ammonia ($\text{NH}_3$) has a central nitrogen atom bonded to three hydrogen atoms and one lone pair, resulting in a trigonal pyramidal geometry.
• The correct option is B.

$$\boxed{\text{B}}$$

26. Electron geometry around O in $\text{H}_2\text{O}$ is:

• Water ($\text{H}_2\text{O}$) has a central oxygen atom with two bonding pairs and two lone pairs, giving it a tetrahedral electron geometry.
• The correct option is D.

$$\boxed{\text{D}}$$

27. Molecular geometry of $\text{CO}_2$ is:

• Carbon dioxide ($\text{CO}_2$) has a central carbon atom double-bonded to two oxygen atoms with no lone pairs, resulting in a linear geometry.
• The correct option is A.

$$\boxed{\text{A}}$$

28. Electron geometry around B in $\text{BF}_3$ is:

• Boron trifluoride ($\text{BF}_3$) has a central boron atom bonded to three fluorine atoms with no lone pairs, giving it a trigonal planar electron geometry.
• The correct option is A.

$$\boxed{\text{A}}$$

29. Molecular geometry of $\text{PF}_5$ is:

• Phosphorus pentafluoride ($\text{PF}_5$) has a central phosphorus atom bonded to five fluorine atoms with no lone pairs, resulting in a trigonal bipyramidal geometry.
• The correct option is A.

$$\boxed{\text{A}}$$

30. Which molecule is nonpolar?

• $\text{CO}_2$ is linear, and its polar C=O bonds cancel out due to symmetry, making the molecule nonpolar.
• The correct option is C.

$$\boxed{\text{C}}$$

31. Which molecule is polar?

• $\text{SO}_2$ has a bent geometry with polar S-O bonds and a lone pair on sulfur, resulting in a net dipole moment, making it polar.
• The correct option is C.

$$\boxed{\text{C}}$$

32. $\text{SO}_2$ geometry is:

• Sulfur dioxide ($\text{SO}_2$) has a central sulfur atom with two bonding pairs and one lone pair, resulting in a bent molecular geometry.
• The correct option is B.

$$\boxed{\text{B}}$$

33. HCN polarity is:

• Hydrogen cyanide (HCN) has a linear structure with a highly polar C≡N bond and a slightly polar C-H bond. The dipoles do not cancel, making it polar.
• The correct option is B.

$$\boxed{\text{B}}$$

34. $\text{CH}_3\text{OH}$ polarity is:

• Methanol ($\text{CH}_3\text{OH}$) contains polar C-O and O-H bonds and has an asymmetric structure, resulting in a net dipole moment, making it polar.
• The correct option is B.

$$\boxed{\text{B}}$$

35. Which molecule has delocalized electrons?

• Ozone ($\text{O}_3$) exhibits resonance, which means it has delocalized electrons.
• The correct option is B.

$$\boxed{\text{B}}$$

36. Which molecule is trigonal pyramidal?

• Ammonia ($\text{NH}_3$) has a central nitrogen atom with three bonding pairs and one lone pair, giving it a trigonal pyramidal geometry.
• The correct option is B.

$$\boxed{\text{B}}$$

37. Which molecule is linear?

• Carbon dioxide ($\text{CO}_2$) has a linear molecular geometry.
• The correct option is B.

$$\boxed{\text{B}}$$

38. Which molecule is nonpolar due to symmetry?

• Carbon tetrachloride ($\text{CCl}_4$) has a tetrahedral geometry. Although the C-Cl bonds are polar, the symmetrical arrangement causes the bond dipoles to