What two things must occur in order for a light ray to refract when it strikes the boundary of a different medium?
A. It must strike the boundary at an angle, and its speed must
change.
B. It must strike the boundary at 45°, and its wavelength must
change.
C. It must strike the boundary at an angle, and its frequency must
change.
D. It must strike the boundary at 45°, and its frequency must change.

Which statement describes how phase changes can be diagrammed as a substance is heated? the phase is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the phase is on the x-axis. the time is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the time is on the x-axis.

Which other elements contain the same number of outer electrons as sodium

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.