Answer:
D: chain of volcanoes circling the Pacific Basin
Explanation:
The Solar System[b] is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly.[c] Of the objects that orbit the Sun directly, the largest are the eight planets,[d] with the remainder being smaller objects, the dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the natural satellites—two are larger than the smallest planet, Mercury.[e]
Answer :
The balanced chemical reaction is,

From this balanced chemical reaction, we conclude that
2 moles of iron oxide react with the 3 moles of carbon to give 4 moles of iron and 3 moles of carbon dioxide.
Therefore, the valid mole ratio from the balanced chemical reaction is,

Answer:
2RbNO₃ + BeF₂ → Be(NO₃)₂ + 2RbF, because Be keeps a 2+ charge throughout the reaction
Explanation:
2RbNO₃ + BeF₂ → Be(NO₃)₂ + 2RbF, because Be keeps a 2+ charge throughout the reaction
Rb is a +1 cation, NO3 is a -1 anion, Be is a +2 cation and F is a -1 anion.
In writing an ionic compound the charge of the cation becomes the subscript of the anion and the charge of the anion becomes the subscript of the cation.
So the ionic compound formed between Be2+ and F- is BeF2. The ionic compound formed between Be2+ and NO3- is Be(NO₃)₂.
As there are two NO₃ on the product side it is balanced by writing a 2 coefficient before RbNO₃ on the reactant side.
And as there are two F on the reactant side it is balanced by writing a 2 coefficient before RbF on the product side.
The balanced reaction is as follows;
BiCl₂ + Na₂SO₄ --> 2NaCl + BiSO₄
this is a double displacement reaction
the oxidation number of Bi is +2 in both BiCl₂ and BiSO₄
oxidation number of Cl is -1 in both BiCl₂ and NaCl
oxidation number of Na is +1 in both Na₂SO₄ and NaCl
oxidation numbers of elements in SO₄²⁻ remains the same in both compounds.Therefore the oxidation state in any of the elements in the reaction doesn't change. Neither of the elements show an increase or decrease in the oxidation numbers .
Answer for this question is no element decreases its oxidation number.