the sum of the enthalpy changes of the intermediate reactions.
the product of the enthalpy changes of the intermediate reactions.
the fraction of the individual enthalpies of the intermediate reactions.
Answer : The correct option is, the sum of the enthalpy changes of the intermediate reactions.
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
For example :
The formation reaction of CO will be,
The intermediate balanced chemical reaction will be,
(1)
(2)
The expression for enthalpy of formation of CO is,
where,
n = number of moles
By adding reaction 1 and reverse reaction of reaction 2, we get the enthalpy of formation of CO.
Hence, the correct option is, the sum of the enthalpy changes of the intermediate reactions.
(a) vacuole (c) chloroplast
(b) nucleus (d) cell membrane
Explanation:
The student most likely observed both (A) Vacuole and (C) Chloroplast that led him to the conclusion, that the cell is a plan cell.
Reason :
In a plant cell, Vacuole occupies 70% to 90% of the total volume of the cell, making it easier to identify.
Chloroplast contains photosynthetic pigment called chlorophyll (green in colour), which is only found in plant cell.
The presence of chloroplasts, containing green pigment chlorophyll for photosynthesis, in the cell likely led the student to conclude it was a plant cell.
The student likely made his conclusion based on observing the presence of chloroplasts in the cell. Chloroplasts contain a green pigment called chlorophyll, which enables plants to undergo photosynthesis and is not found in animal cells. The others listed (vacuoles, cell membrane, and nucleus) are also present in animal cells and therefore would not specifically indicate a plant cell.
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