All changes saved The graph shows the changes in the phase of ice when it is heated.
(-1,0)
= G(x) +R(6)
Q(x)
Phase Change of Ice
D
gas
rin
5.3x10
C
Temperature
(°C)
liquid
B-
solid
25
100
50 75
Time (min)
Which of the following temperatures describes the value of B? (4 points)
O 0 °C, because it is the melting point of Ice.
O 100 °C, because it is the boiling point of water.
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ALB
O Greater than 0 °C, because A represents the temperature at which ice melts.
BLIC SC
O Greater than 100 °C, because A represents the temperature at which water evaporates.

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.