B. 1 kiloparsec
C. 1 light-year
D. 1 AU
The distance between the Earth and the Sun is approximately 1 AU (Astronomical Unit). Therefore, option D is correct.
One AU is defined as the average distance between the Earth and the Sun, which is about 93 million miles (150 million kilometers). It is a convenient unit of measurement for distances within our solar system.
A parsec is a unit of distance used for objects outside our solar system, equal to approximately 3.26 light-years. One kiloparsec is equal to 1,000 parsecs, or approximately 3,260 light-years. Therefore, neither A nor B is the correct answer.
A light-year is the distance that light travels in one year, which is approximately 5.88 trillion miles (9.46 trillion kilometers). Therefore, C is also not the correct, as the distance between the Earth and the Sun is much less than one light-year.
Therefore, the correct answer is D. 1 AU
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Explanation:
Electronegativity is the chemical property of an element. This is defined as the tendency of an atom to attract the shared pair of electrons towards itself when a bond is formed.
A.
Only the Fe is unbalanced.
B.
Only the O is unbalanced
C.
Fe and O are both unbalanced.
D.
C and O are both unbalanced
These are two questions and two answers.
Question 1: Law of Conservation of Mass
Answer: option B. The total mass remains the same during a chemical reaction.
Explanation:
The law of conservation of mass is a universal law. It states that mass is mass is neither created or destroyed, but is is conserved.
In chemical reactions, that means that, always, the total mass of the reactants equals the total mass of the products or, as the option B. states, during a chemical reaction the total mass remains the same.
Since, in chemical reactions, the atoms are not modified (the atoms just bond in different form or with different atoms), that implies that total number of each kind of atoms in the reactants equals the total number of the same kind of atoms in the products.
That is the basis for balancing the chemical equations and for the stoicheometric calculations.
Question 2 . Which element(s) are not balanced in this equation?
Answer: option A. Only the Fe is unbalanced.
Explanation:
1) Given equation: Fe₂O₃ + 3 CO → Fe + 3 CO₂
2) Count the number of atoms of each kind on each side of the equation
i) Fe
reactant side: 2
product side: 1
Therefore, Fe is not balanced
ii) O
reactant side: 3 + 3 = 6
Product side: 3 × 2 = 6
Therefore, it is balanced
iii) C
reactant side: 3
product side: 3
Therefore, C is balanced.
3) Conclusion: Only the Fe is unbalanced.
For #1, the answer is B. The total mass remains the same during a chemical reaction.
For #2, given Fe2O3 + 3CO -> Fe + 3CO2
Fe is unbalanced, and O is also unbalanced
Therefore, Option C: Fe and O are both unbalanced, is true.