The answer is C :), I think.
The graph is missing, however we can answer anyway.
In fact, this is the approximate percentage of the elements listed in the questions in the Earth's crust (data taken from wikipedia):
Iron 5.0 %
Calcium 3.6 %
Sodium 2.8 %
Potassium 2.6 %
Magnesium 1.5 %
of all of these, we see that the combination of two elements that makes up the closest number to 7% is calcium and sodium (3.6% + 2.8%=6.4%), therefore the correct answer is
Calcium and sodium.
Magma<span> is made up of molten rock, and it is stored in Earth's crust. </span><span> When the volcano erupts, magma flows out of the volcano, it is usually mixed with steam and gas, which is called lava.</span>
Answer:
2 ans : the bell has 8550 J energy
