What kind of energy transfer
Answer:
0.13 s
Explanation:
We'll begin by converting 24900 mile to metres (m). This can be obtained as follow:
1 mile = 1609.344 m
Therefore,
24900 mile = 24900 mile × 1609.344 m / 1 mile
24900 mile = 4.01×10⁷ m
Finally, we shall determine the time taken for light to circumnavigate the Earth, this can be obtained as follow:
Distance = 4.01×10⁷ m
Speed = 2.998×10⁸ m/s
Time =?
Speed = distance / time
2.998×10⁸ = 4.01×10⁷ / time
Cross multiply
2.998×10⁸ × time = 4.01×10⁷
Divide both side by 2.998×10⁸
Time = 4.01×10⁷ / 2.998×10⁸
Time = 0.13 s
Thus, it will take 0.13 s for light to circumnavigate the Earth.
Answer:
Choice A: carbon-12,
.
Explanation:
- The number on the top-left corner of each particle is its mass number.
- The number on the lower-left corner of each particle is its atomic number.
Let
- the mass number of X be A, and
- the atomic number (a.k.a. proton number) of X be Z.
Symbol of X:
.
Consider the two conservation laws:
- Sum of mass numbers on the left-hand side = Sum of mass numbers on the right-hand side.
- Sum of atomic numbers on the right-hand side = Sum of atomic numbers on the right-hand side.
Sum of mass numbers:
- Left-hand side: 9 + 4;
- Right-hand side: A + 1.
Equate the two sides:

.
Thus the mass number of X is 12.
Try the steps above to find the atomic number of X. The number
on the lower-left corner of
indicates that the atomic number of this neutron is zero.
.
Thus the atomic number of X is 6.
What element is X? Refer to a modern periodic table. The element with atomic number 6 is carbon. The symbol for carbon is
. The mass number of this isotope is 12. The answer will be
.