What is the term for the pattern of spiral impressions inside a handgun?

a) rifling
b) ejector markings
c) lands and grooves
d) extractor markings

What is the energy of a photon of ultraviolet radiation with a frequency of 4.4 × 1015 hz? planck’s constant is 6.63 × 10–34

Determine the age of a fossil if it had only one eighth of its original carbon-14 content remaining?

Nacidified solution was electrolyzed using copper electrodes. a constant current of 1.18 a caused the anode to lose 0.584 g after 1.52 ✕ 103 s. given that the charge of an electron is 1.6022 ✕ 10−19 c, calculate avogadro's number. assume that copper is oxidized to cu2+ ions.