Answer:
A). The complementary shapes of an enzyme and a substrate.
Explanation:
The Lock-and-key mechanism was proposed by Emil Fischer for the first time and characterized as the metaphor which helps in elucidating the specificity of the enzymatic reactions. In this metaphor, the lock is described as the enzyme while 'key' is characterized as the substrate which the enzyme acts upon. If the key is not appropriately sized, it will not fit into the active site i.e. the keyhole of the lock or enzyme and reaction will not take place. Thus, <u>option A</u> is the correct answer.
The reaction will produce 12.1 g Ag₂S.
<em>Balanced equation</em> = 2Ag + S ⟶ Ag₂S
<em>Mass of Ag₂S</em> = 10.5 g Ag × (1 mol Ag/107.87 g Ag) × (1 mol Ag₂S/2 mol Ag)
× (247.80 g Ag₂S/1 mol Ag₂S) = 12.1 g Ag₂S
The changes that are common between sauce burning on a stove, and jewelry tarnishing, which is a chemical change.
How to define chemical and physical changes?
Chemical Change-
Any alteration that produces new chemical substances with distinct properties is considered a chemical change. Chemical reactions involve the rearrangement and recombination of elements and compounds to create new substances. Examples of chemical changes are listed below:
- Burning
- Digestion
- chemicals changing colors
- Tarnishing
- compost rotting
Physical Change-
A substance is not destroyed or transformed into something new by physical changes. A substance can undergo physical changes that alter its shape, size, or phase. The constituents of an element or compound do not change during a physical change. Examples of physical changes are listed below:
- Boiling water
- Chopping, Cutting, Carving
- Evaporation
- Freezing, Melting, Condensation
To know more about chemical and physical changes, visit the given link:
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Answer:
A. 
B. 
Explanation:
Hello!
In this case, since the undergoing chemical reaction between nitrogen and hydrogen is:

Thus we proceed as follows:
A. Here, we first need to compute the moles of ammonia yielded by each reactant, in order to identify the limiting one:

Thus, since nitrogen yields the fewest moles of ammonia, we realize it is the limiting reactant, so the theoretical yield, in grams, of ammonia is:

B. Finally, since the actual yield of ammonia is 1.23, the percent yield turns out:

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