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.
Hi there!
In this instance, the object spinning in a horizontal circle will experience a net force in the horizontal direction due to tension.
The net force is equivalent to the centripetal force, so:
∑F = T
mv²/r = T
Solve for v:
v = √rT/m
v = 13.96 m/s
Answer:
i think it would be B. Aluminum, Al and D. Boron, B
Explanation:
since they're both in group 13 and they forms a 3+ ion
