Consider a solution consisting of the following two buffer systems:

H2CO3 HCO3– + H+ pKa = 6.4

H2PO4– HPO42– + H+ pKa = 7.2
At pH 6.4, which one of the following is true of the relative amounts of acid and conjugate base present?
***Please explain why the right answer is right and why the other ones are wrong.

a. [H2CO3] > [HCO3- ] and [H2PO4- ] > [HPO42- ]

b. [HCO3- ] > [H2CO3] and [HPO42- ] > [H2PO4- ]

c. [H2CO3 ] > [HCO3- ] and [HPO42- ] > [H2PO4- ]

d. [H2CO3] = [HCO3-] and [HPO42-] > [H2PO4- ]

e. [H2CO3] = [HCO3-] and [H2PO4- ] > [HPO42-]

The drawing represents the movement of particles in a substance. what changes of state can this substance undergo

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.

100 grams of molten lead (600°c) is used to make musket balls. if the lead shot is allowed to cool to room temperature (21°c), what is the change in entropy (in j/k) of the lead? (for the specific heat of molten and solid lead use 1.29 j/g⋅°c; the latent heat of fusion and the melting point of lead are 2.45 × 104 j/kg and 327°c, respectively.)