Question

40 multiple choice 1 point
what type of bond will typically form between boron and hydrogen based on their electronegativity?
metallic
covalent
ionic

41 multiple choice 1 point
based off molecular polarity determined by vsepr theory, which of the following would be soluble in methanol (\\(\text{ch}_3\text{oh}\\))?
heptane (\\(\text{c}_7\text{h}_{16}\\))
pentane (\\(\text{c}_5\text{h}_{12}\\))
ethanol (\\(\text{ch}_3\text{ch}_2\text{oh}\\))

42 multiple choice 1 point
what is the correct formula for lead(ii) nitrate?
\\(\text{pb}(\text{no}_3)_2\\)
\\(\text{pd}(\text{no}_3)_2\\)
\\(\text{pb}(\text{no}_3)\\)

43 multiple choice 1 point
using vsepr theory, predict the molecular shape and bond angles in \\(\text{bcl}_3\\).
trigonal pyramidal, \\(120^\circ\\)
trigonal bent, \\(120^\circ\\)
trigonal planar, \\(120^\circ\\)

44 multiple choice 1 point
the formula for potassium cyanide is \\(\text{kcn}\\) and the formula for calcium fluoride is \\(\text{caf}_2\\). what is the formula for calcium cyanide?
\\(\text{ca}(\text{cn})_2\\)
\\(\text{cacn}\\)
\\(\text{ca}_2\text{cn}\\)

Explanation:

Analyze bond type between boron and hydrogen

Using the Covalent Bond Sharing knowledge point:
Boron (\(\text{B}\)) has an electronegativity of approximately \(2.04\), and hydrogen (\(\text{H}\)) is \(2.20\). The electronegativity difference is very small (\(0.16\)), meaning electrons are shared relatively equally. Therefore, they typically form a covalent bond.

Determine solubility in methanol

Using the VSEPR Theory knowledge point:
Methanol (\(\text{CH}_3\text{OH}\)) is a highly polar solvent capable of hydrogen bonding. According to the "like dissolves like" rule, polar solutes dissolve in polar solvents. Ethanol (\(\text{CH}_3\text{CH}_2\text{OH}\)) is polar and can hydrogen bond, making it highly soluble in methanol, whereas heptane and pentane are nonpolar hydrocarbons.

Determine formula for lead(II) nitrate

Using the Chemical Nomenclature knowledge point:
Lead(II) indicates a \(\text{Pb}^{2+}\) cation. Nitrate is a polyatomic anion with the formula \(\text{NO}_3^-\). To balance the charges, two nitrate ions are needed for every lead(II) ion, yielding \(\text{Pb(NO}_3)_2\).

Predict molecular shape of BCl3

Using the VSEPR Theory knowledge point:
Boron has 3 valence electrons and forms 3 single bonds with chlorine atoms, leaving no lone pairs on the central boron atom. This steric number of 3 results in a trigonal planar geometry with ideal bond angles of \(120^\circ\).

Determine formula for calcium cyanide

Using the Chemical Nomenclature knowledge point:
From \(\text{KCN}\), we identify the cyanide ion as \(\text{CN}^-\). From \(\text{CaF}_2\), we identify the calcium ion as \(\text{Ca}^{2+}\). Combining one \(\text{Ca}^{2+}\) with two \(\text{CN}^-\) to balance the charge gives \(\text{Ca(CN)}_2\).

Answer:

Question 40

• metallic
• covalent (Correct answer)
• ionic

Question 41

• heptane (\(\text{C}_7\text{H}_{16}\))
• pentane (\(\text{C}_5\text{H}_{12}\))
• ethanol (\(\text{CH}_3\text{CH}_2\text{OH}\)) (Correct answer)

Question 42

• \(\text{Pb(NO}_3)_2\) (Correct answer)
• \(\text{Pd(NO}_3)_2\)
• \(\text{Pb(NO}_3)\)

Question 43

• trigonal pyramidal, \(120^\circ\)
• trigonal bent, \(120^\circ\)
• trigonal planar, \(120^\circ\) (Correct answer)

Question 44

• \(\text{Ca(CN)}_2\) (Correct answer)
• \(\text{CaCN}\)
• \(\text{Ca}_2\text{CN}\)