The
benefit of using a shortcut in a reaction between two chemicals is
that sings of a chemical change will still be found. We will still
get a new substance and its chemical and physical properties will
differ from those of the original substance.
I
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Answer:
<em> A. 38%</em>
Explanation:
Percentage increase in carbon dioxide concentration = (Increase in concentration of carbon dioxide/initial concentration)×100
P = (C₂-C₁/C₁)×100...................... Equation 1
Where P = percentage increase in the concentration of carbon dioxide from 1970 to 2007, C₁ = The atmospheric concentration of carbon dioxide in 1970, C₂ = The atmospheric concentration of carbon dioxide in 2007.
<em>Given: C₁ = 278 ppm, C₂ = 383 ppm.</em>
Substituting these values into equation 1
<em>P = [(383-278)/278]×100</em>
<em> P = (105/278)×100</em>
<em>P = 37.7%</em>
<em>P ≈ 38%</em>
<em>Thus the approximate percentage increase in carbon dioxide concentration from 1790 to 2007 is 38%</em>
<em>The right option is A. 38%</em>
<em />
Answer:
D. 200%
Explanation:
While Americans constitute the 5% of the world population, they use around the 24% of the world's energy.
Then, if the 100% of the population were like the Americans, we have:
5%*x = 100%
x = 100%/5% = 20
the whole population is 20 times the population of the US, then the total energy used is 20 times the energy used in the US.
Then the energy that the 100% of the population would use is equal to:
20*24% = 480%
So we actually would need like 5 Earths.
The option is 200%
Answer:
M
=
2.0
m
o
l
L
−
1
Explanation:
The molarity,
M
of this solution can be calculated by a formula which is;
M
=
n
V
where;
M
= Molarity of solution
n
=Number of moles of solute
V
= Volume of solution in Litre
Given,
n
=
4.0
moles and
V
=
2.0
L, so we have enough information to calculate the molarity of the solution;
M
=
n
V
M
=
4.0
2.0
m
o
l
L
−
1
M
=
2.0
m
o
l
L
−
1
or
M
=
2.0
m
o
l
d
m
−
3
if the questions mention volume of solution in
d
m
3
because
L
=
d
m
3
