* not completed

. Which of the following ores is the principal for the early lanthanoids?

monazite correct incorrect

xenotime correct incorrect

pitchblende correct incorrect

* not completed

. Are all actinoids radioactive?

yes correct incorrect

no, none are correct incorrect

some are and some are not correct incorrect

* not completed

. The mixtures of early lanthanoids, industrially known as mischmetal, are used in:

cathode ray displays correct incorrect

solid state lasers correct incorrect

steel making correct incorrect

* not completed

. Select the correct statement:

Lanthanoids are highly electronegative and favor -3 oxidation state. correct incorrect

Lanthanoids are highly electropositive and favor +3 oxidation state. correct incorrect

Lanthanoids are highly electronegative and do not favor any particular oxidation state. correct incorrect

* not completed

. What types of binary ionic compounds are well-known for all lanthanides?

oxides and halides only correct incorrect

hydrides and nitrides only correct incorrect

oxides, halides, hydrides, and nitrides correct incorrect

* not completed

. Which ternary and complex lanthanoid oxides are an important ferrimagnetic material for microwave and optical communication devices?

the LaFeO₃ type pervskite correct incorrect

the Y-Al garnet correct incorrect

the Y-Fe garnet correct incorrect

* not completed

. Lanthanoids form coordination compounds that:

possess low coordination numbers with geometries that can accommodate high interligand repulsions correct incorrect

possess high coordination numbers with geometries that can minimize interligand repulsions correct incorrect

possess high coordination numbers with geometries that can accommodate high interligand repulsions correct incorrect

* not completed

. In organometalic compounds of lanthanoids, ligands such as _____ and _____ are common, while ligands such as _____ and _____ are rare.

CO and phosphine; alkoxide and amide correct incorrect

CO and alkoxide; phosphine and amide correct incorrect

alkoxide and Cp^-; CO and amide correct incorrect

* not completed

. The most stable oxidation states for Th and U are:

+4 and +6 for U; 4 for Th correct incorrect

+4 and +6 for Th; +4 for U correct incorrect

+6 for both U and Th correct incorrect

* not completed

. Why are chemical properties of uranium more varied that that of thorium?

Because uranium is more abundant tan thorium, resulting in more work done on uranium chemistry. correct incorrect

Because uranium can adopt more oxidation states than thorium, hence uranium forms more compounds than thorium. correct incorrect

Because thorium is more radioactive than uranium and thus more difficult to handle. correct incorrect