If the density of copper (Cu) is 8.96 g/cm3 and that of zinc (Zn) is 7.13 g/cm3. Calculate and compare the volume of a pre-1982 penny to that of a post-1982 penny? Give one reason to support your answer

Which of the following signs of a chemical reaction are observed in the reaction of potassium with water? precipitate formed temperature change smell produced gas produced color change

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.

Why is retrograde motion an apparent motion