<h2>Answer:</h2>
Option (B):
The products can form reactants, and the reactants can form products.
<h3>Explanation:</h3><h3>Reversible reaction</h3>
A reversible reaction is a reaction where the reactants form products, which react together to give the reactants back.
aA + bB ⇄ cC + dD
A and B can react to form C and D or, in the reverse reaction, C and D can react to form A and B.
Other options are wrong because off:
(A) Concentration changes with time equilibrium concentration and higher product concentration is also possible.
(C) They may be constant.
(D) Concentration changes with time equilibrium concentration and higher reactant concentration is also possible.
Conjugated dienes routinely undergo 1,2 and 1,4 addition reactions with a variety of electrophilic reagents; this suggests that electrophilic reagents are likely intermediates during these reactions.
Two double bonds and one single bond divide a conjugated diene into two halves. Nonconjugated (Isolated) Dienes have more than one single bond separating two double bonds. Two double bonds are joined to the same atom to form cumulated dienes.
Reagents that function by acquiring electrons or sharing electrons that once belonged to a foreign molecule are referred to as electrophilic reagents, or electrophiles, in some cases. Electrophiles are molecules with a positive charge and a lack of electrons that can react by exchanging electron pairs with nucleophiles, which have many electrons. Epoxides, hydroxy amines, nitroso and azoxy derivatives, nitrenium ions, and elemental sulfur are significant electrophiles.
To know more about Electrophiles refer to: brainly.com/question/21773561
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Answer: Number of molecules of hydrogen gas 
Explanation:

Number of moles of sodium =
According to reaction , 2 moles of sodium produces 1 mole of hydrogen gas , then 2.11 mol of sodium will=
of hydrogen gas that is 1.05 moles of hydrogen gas.
Number of molecules =
moles of substance
Moles of hydrogen gas formed = 1.05 moles
Number of molecules of hydrogen gas =
moles of hydrogen gas
Number of molecules of hydrogen gas 
Answer:
The number of moles of the gas is 9.295 moles or 9.30 moles
Explanation:
We use PV = nRT
Where P = 4.87 atm;
V = 67.54 L
R= 0.0821Latm/molK
T = 158 C = 158 +273 K = 431 K
the number of moles can be obtained by substituting the values in the respective columns and solve for n
n = PV / RT
n = 4.87 * 67.54 / 0.0821 * 431
n = 328.9198 / 35.3851
n = 9.295moles
The number of moles is approximately 9.30moles.