Rust (Fe2O3. 4H2O) is formed when iron interacts slowly with oxygen and water. Mass of Fe in grams is 2.18 x 10⁴ g.
<h3>
What is the explanation?</h3>
There are 2 moles of Fe atoms in 1 mole of Fe2O3-4H2O. The number of moles of Fe atoms in 45.2 kg rust is shown below.
Moles of Fe = 195.01 mol Fe₂O₃.4H₂O ( 
)
Moles of Fe = 390.02 mol Fe
Multiply the calculated number of moles of iron, Fe, by its molar mass which is 55.85 
Mass of Fe = 390.02 mol Fe ( 
)
Mass of Fe = 2.18 x 10⁴ g Fe
Avogadro's number (6.022 x 1023) of molecules (or formula units) make up one mole of a substance (ionic compound). The mass of 1 mole of a chemical is indicated by its molar mass. It provides you with the amount of grams per mole of a substance, to put it another way.
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The standard enthalpy of reaction should be negative.
<h3>What is enthalpy?</h3>
A thermodynamic quantity equivalent to the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume.
Inside the heat pack are two chemicals that get mixed when you smush them together. As they mix, some weak bonds are broken, which takes a little bit of energy. But new, stronger bonds form which release energy. Releasing that energy causes the surroundings to heat up.
Hence, option B is correct.
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Answer:
4 moles
Explanation:
= 
= 2 (moles)
CH4 + 2O2 → CO2 + 2H2O
1 : 2 : 1 : 2
2 (moles)
⇒ 
= 2 × 2 ÷ 1 = 4 (moles)
<u>Answer:</u> The correct answer is Option 4: U
<u>Explanation:</u>
Activation energy is defined as the energy that is given to a chemical system with potential reactants to produce products. It is represented as 
It is represented as the energy from the reactants to the activated complex.
Reverse reaction is defined as the reaction in which the products formed become reactants and leads to the formation of reactants back.
So, here, the activation energy of the reverse reaction is the energy between the products and the activated complex, which is represented as letter U in the given graph.
Hence, the correct answer is Option 4: U
