MCQ Collection
ECAT MCQs
Practice ECAT questions with answers and explanations.
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Correct Answer: C. Total microscopic kinetic and potential energy of a system
Explanation:
Internal energy includes molecular motion, bonding, and interactions.
Only changes in internal energy are directly measured.
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Correct Answer: C. Products are strongly favored at equilibrium
Explanation:
A large K means the equilibrium mixture contains mostly products.
It does not directly indicate reaction speed.
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Correct Answer: D. A thermodynamic property equal to internal energy plus pressure-volume term
Explanation:
Enthalpy is H=U+PV.
At constant pressure, enthalpy change equals heat transferred for PV work.
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Correct Answer: D. Reactants are strongly favored at equilibrium
Explanation:
A small K means little product is present at equilibrium.
The forward reaction may still occur.
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Correct Answer: A. A process releasing heat to the surroundings
Explanation:
Exothermic processes have negative enthalpy change under the usual convention.
The surroundings gain heat.
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Correct Answer: B. A process absorbing heat from the surroundings
Explanation:
Endothermic processes have positive enthalpy change.
The system gains heat.
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Correct Answer: C. Heat required to raise an object's temperature by one degree
Explanation:
Heat capacity depends on the amount and identity of matter.
Specific heat capacity is heat capacity per unit mass.
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Correct Answer: D. Measurement of heat changes
Explanation:
Calorimeters track temperature changes in known heat capacities.
They help determine reaction or phase-change energy.
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Correct Answer: A. Overall enthalpy change is the sum of enthalpy changes for any reaction pathway
Explanation:
Enthalpy is a state function.
Therefore the path between initial and final states does not affect ΔH.
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Correct Answer: B. Enthalpy change forming one mole of compound from elements in standard states
Explanation:
Standard formation enthalpies are tabulated reference values.
Elements in their standard states have ΔHf° defined as zero.
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Correct Answer: C. Pressure a gas would exert alone in the mixture volume
Explanation:
Dalton's law treats each ideal gas independently.
Total pressure is the sum of partial pressures.
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Correct Answer: C. 0.987 mol
Explanation:
Use n=PV/RT.
N=100×24.6/(8.31×300)≈0.987 mol.
