(3)what are the only elements that exist in nature as uncombined atoms? what term is used to describe such elements? hint

What is the percentage by mass of silicon (si) in iron aluminum silicate (fe3al2(sio4)3)?

What is the main purpose of patent attorneys? defend the company against legal claims manage financial investments invent new products protect rights to new products and processes

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.