The energy needed to raise the temperature of water from 22.0ºC to 90.0ºC is c. 28.4 kJ.
<h3>What is specific heat?</h3>
The amount of energy needed to raise the temperature of one gram of a substance by one degree Celsius.
By the formula 
Q is the heat
m is the mass
c is the specific heat
Now, c = 4.184 J/g.K
The change in temperature is 22.0 ºC to 90.0 ºC
Putting the value in the equation

Thus, the energy needed to raise the temperature of water from 22.0ºC to 90.0ºC is 28.4 kJ
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Answer:
A decomposition reaction
Explanation:
It is a decomposition reaction where a single type of chemical compound breaks down into two or more elements or new compounds.
Answer:
Percentage abundance of B 10 is = 20 %
Percentage abundance of B 11 is = 80 %
Explanation:
The formula for the calculation of the average atomic mass is:
Given that:
Since the element has only 2 isotopes, so the let the percentage of first be x and the second is 100 -x.
For first isotope, B 10:
% = x %
Mass = 10.0129 u
For second isotope, B 11:
% = 100 - x
Mass = 11.0093 u
Given, Average Mass = 10.81 u
Thus,

Solving for x, we get that:
x = 20 %
Thus percentage abundance of B 10 is = 20 %
Percentage abundance of B 11 is = 100 - 20 % = 80 %
<span>The dependent variable is the variable which is the result of the changing experimental variable. In this case, how far the rock went is a result of changing the angle of launch. Therefore, how far the rock went is the dependent variable.</span>