How many oxide ions (O-2) are needed to balance the positive charge of a titanium ion (Ti+4)?

Strontium, Sr (number 38), is especially dangerous to humans because it tends to accumulate in calcium-dependent bone marrow tissues (calcium, Ca, number 20). This fact relates to the organization of the periodic table in that strontium and calcium are both

Identify the following image by title, date or time period, and culture/country of origin:  

The Jewish site at Dura-Europos in Syria functioned as a/an:

This element of a Romanesque cathedral consists of imagery in a lunette over a door lintel:

A horseshoe arch features prominently in this type of architecture:

The Bayeux Tapestry commemorates the:

This group of attendant votive statues found at Eshnunna in Iraq once functioned:

The cloisonné technique involves:

Provide the titles, artists, and dates for the following images. Compare and contrast the two images: What is the subject matter? How are the works the same? How are they different? Answer in at least one paragraph.