Answer:
B) As you move across the row, the number of electrons increases and reactivity also increases.
Explanation:
The periodic table is arranged in a way that if you go across a period, the number of protons, neutrons, and electrons in an element increases. In terms of reactivity, the most reactive elements are the ones which have a high electronegativity. The electronegativity of the elements increases as you travel to the right and upwards on the periodic table.
Answer: 
Explanation: A double displacement reaction is one in which exchange of ions take place.
The compounds which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Thus the exchange of ions take place and all the compounds are soluble so the chemical formulas are followed by the symbol (aq).
Hello. This question is incomplete. The full question is:
"Consider the following reaction. 2NO(g) + 2H2(g) → N2(g) + 2H2O(g)
A proposed reaction mechanism is: NO(g) + NO(g) N2O2(g) fast N2O2(g) + H2(g) → N2O(g) + H2O(g) slow N2O(g) + H2(g) → N2(g) + H2O(g) fast
What is the rate expression? A. rate = k[H2] [NO]2 B. rate = k[N2O2] [H2] C. rate = k[NO]2 [H2]2 D. rate = k[NO]2 [N2O2]2 [H2]"
Answer:
A. rate = k[H2] [NO]2
Explanation:
A reaction mechanism is a term used to describe a set of phases that make up a chemical reaction. In these phases a detailed sequence of each step is shown, composed of several complementary reactions, which occur during a chemical reaction.
These mechanisms are directly related to chemical kinetics and allow changes in reaction rates to be observed in advance.
Reaction rate, on the other hand, refers to the speed at which chemical reactions occur.
Based on this, we can observe through the reaction mechanism shown in the question above, that the action "k [H2] [NO] 2" would have no changes in the reaction rate.
We know that when calculating percent yield, we use the equation:

Since the quantities that we are given in the question are equal, we can just directly divide them to find percent yield:

So now we know that the percent yield of the synthesis is 87.27%.
The answer is D, because gems are usually not mettallic