The Greek sea god Poseidon corresponds to which Roman god?

"Physical" by which singer was No. 1 on the charts longer than any other song of the 1980s? How many playing squares are on a standard chessboard? Polynomials and coefficients are used in which branch of math? Pop singer Yvonne Elliman played Mary Magdalene in which 1973 musical film? President Clinton's torn tendon in 1997 was an injury to which joint? What was President Reagan's alliterative description of the USSR, which he softened at a 1988 summit? Made mostly of calcium compounds, what is the main tissue beneath a tooth's enamel? IKEA founder Ingvar Kamprad famously drove an old 240 GL from which European auto company?