What is the gas ‘Xenon’ also known as?

? = 41.92% of 49.96% of (45.07 ^1.97 – 4.98 ^2.03 )

25.902 × 78.095 + 999.996% of 200.08 + 20.005 % of 7999.997 = ? × 15.008 × 33.009

11.67 × 50.23 + ? = 14.88% of 600.44 + 9.66 × 8.27² 

³√? × 33.97 + 59.99 × 28.9 – 48.98 × 21.42 = 1085.344

509.85 ÷ 15.05 + 210.16 – 18.06 × 5.95 = ?

9.99% of 19.86% of 30.23% of (11999.84 × 9.68) = ?

[54.96 × √99.96 – {(25.02/6.84)% of 280.24}]/(3.03² × 19.87) = ?

(3/8) × 479.84 + (2/5) × 449.67 = ? × 12.25 

(29.97%) of 9840 + ? + (45.17% of 1240) = (31.955% of 11750)