Line spectra from all regions of the electromagnetic spectrum, including the paschen series of infrared lines for hydrogen, are used by astronomers to identify elements present in the atmospheres of stars. calculate the wavelength of the photon emitted when the hydrogen atom undergoes a transition from n = 5 to n = 3. (r = 2.179 x 10-18 j r = 1.096776 x 10^7 m-1) a. 205.1 nm b. 384.6 nm c. 683.8 nm d. 1282 nm e. > 1500 nm

Choose all the answers that apply. as ocean depth increases, temperature decreases temperature increases pressure increases pressure decreases salinity increases density increases

The scheme below is from a series of reactions that are part of a synthesis of vitamin a. answer the following questions with reference to this scheme. (i) what is "reagent a"? (ii) draw a step-by-step mechanism which explains the formation of compound c from compound b (iii) which reagents would you use to form compound e from compounds c and d (reagents b and c)? for each reagent suggested above in (ii) explain the role of the reagent in the reaction to (iv) form compound e. you may wish to do this by drawing a mechanism. 1. addition of reagent a но reagent a 2. н,о" thо oh нон-с compound a. compound b. compound c .ch-оh 1. reagent b "сно 2. reagent c сh oh compound e. compound d.

Acrystal that absorvd water from air is (blank)a. aqueousb. homogenousc. hygroscopicd. efflorescent