Question: The Gurjar Pratihar Empire acted as a barrier for Arab invaders from the 8th to the 11th century. The chief accomplishment of the Gurjara Pratihara empire lies in its successful resistance to foreign invasions from the west, starting in the days of Junaid. Historian R. C. Majumdar says that this was openly acknowledged by the Arab writers. He further notes that historians of India have wondered at the slow progress of Muslim invaders in India, as compared with their rapid advance in other parts of the world. Now there seems little doubt that it was the power of the Gurjara Pratihara army that effectively barred the progress of the Arabs beyond the confines of Sindh, their first conquest for nearly 300 years.
Try to answer this question if possible: For how long did the Arab empire stand?
Answer: unanswerable
Question: In the colonial years, while conditions were more fluid, white women, indentured servant or free, and African men, servant, slave or free, made unions. Because the women were free, their mixed-race children were born free; they and their descendants formed most of the families of free people of color during the colonial period in Virginia. The scholar Paul Heinegg found that eighty percent of the free people of color in North Carolina in censuses from 1790–1810 could be traced to families free in Virginia in colonial years.
Try to answer this question if possible: What happened to mixed-race children from mothers who were enslaved?
Answer: unanswerable
Question: Much of mandolin development revolved around the soundboard (the top). Pre-mandolin instruments were quiet instruments, strung with as many as six courses of gut strings, and were plucked with the fingers or with a quill. However, modern instruments are louder—using four courses of metal strings, which exert more pressure than the gut strings. The modern soundboard is designed to withstand the pressure of metal strings that would break earlier instruments. The soundboard comes in many shapes—but generally round or teardrop-shaped, sometimes with scrolls or other projections. There is usually one or more sound holes in the soundboard, either round, oval, or shaped like a calligraphic F (f-hole). A round or oval sound hole may be covered or bordered with decorative rosettes or purfling.
Try to answer this question if possible:  What are the sound holes opened with?
Answer: unanswerable
Question: When an inductive circuit is opened, the current through the inductance collapses quickly, creating a large voltage across the open circuit of the switch or relay. If the inductance is large enough, the energy will generate a spark, causing the contact points to oxidize, deteriorate, or sometimes weld together, or destroying a solid-state switch. A snubber capacitor across the newly opened circuit creates a path for this impulse to bypass the contact points, thereby preserving their life; these were commonly found in contact breaker ignition systems, for instance. Similarly, in smaller scale circuits, the spark may not be enough to damage the switch but will still radiate undesirable radio frequency interference (RFI), which a filter capacitor absorbs. Snubber capacitors are usually employed with a low-value resistor in series, to dissipate energy and minimize RFI. Such resistor-capacitor combinations are available in a single package.
Try to answer this question if possible: What type of capacitor absorbs radio frequency interference?
Answer:
a filter capacitor