The best wavelengths of visible light for photosynthes's fall within the blue range (425-450 nanometers) and red range (600-700 nanometers). Calculate the frequency of a blue licht a wavelength of 4.30 x 10 meters
129 H7
1.43 x10-15 HZ
6.93 × 1014 Hz
6,98 HZ
143 hz

How does chemistry affect our world? a. chemicals makes our world more polluted. b. chemicals keeps us healthy. c. chemicals can or hurt our world. d. chemicals make our world safe to live in.

Based on the law of conservation of energy, which statement is false? answer- energy is lost when machines dont work right

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)