Explanation:
Pure subsance is a substance that is made up of only one type of particle - each piece is the same throughout.
Being present before the reaction but not after means it's no the same (it couldve evaporated)
Answer : The mass of
required is 18.238 grams.
Explanation : Given,
Mass of
= 83.10 g
Molar mass of
= 146 g/mole
Molar mass of
= 256.52 g/mole
The balanced chemical reaction is,

First we have to determine the moles of
.

Now we have to determine the moles of
.
From the balanced chemical reaction we conclude that,
As, 8 moles of
produced from 1 mole of 
So, 0.569 moles of
produced from
mole of 
Now we have to determine the mass of
.


Therefore, the mass of
required is 18.238 grams.
Answer:
Exothermic reaction for the HCl, endothermic reaction for the water

Explanation:
Heat was lost by HCl as its temperature lowered, so it was an exothermic reaction for the HCL.
Heat was gained by water as its temperature increased, so it was an endothermic reaction for the water.
m = Mass of water = 100 g
c = Specific heat of water = 
= Change in temperature of water = 
Heat is given by

Heat gained by water is
.
a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
- a person or thing that precipitates an event.
Answer:
- <u><em>g) Neither plant should increase by 1 cm in height.</em></u>
Explanation:
See the graph for this question on the figure attached.
The growing of the <em>plant A</em> is represented by the line that goes above the other. At start, that line has a slope that rises about 0.75 cm ( height increase) in 1 day. From the day 2 and forward the slope of the line decreases. The line reaches its highest point about at day 4 and seems to start decreasing. Thus, you should predict that on the day six it <em>most likely </em>does not increase in height.
The growing of the <em>plant B</em> is represented by the line drawn below the other. As for the plant B, the growing decreases with the number of days. Between the days 4 and 5 the line is almost flat, which means that <em>most likely</em> this plant will not grow on the day six or grow less than 0.5 cm.
Thus, for both plants you can say that <em>on day six, most likley, neither should increase by 1 cm in height (</em>option g).