NEET Practice Questions (MCQs) with Answers & Solutions

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The spontaneous flow of heat is always

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Explanation

The spontaneous flow of heat is always unidirectional from higher temperature to lower temperature. This is in accordance with the second law of thermodynamics, which states that heat naturally flows from a hot object to a cooler one until thermal equilibrium is reached.

The occurrence of a reaction is impossible if

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Identify the correct statement regarding entropy

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Explanation

According to the third law of thermodynamics, the entropy of a perfectly crystalline substance is zero at absolute zero temperature (0 Kelvin). This is because a perfectly crystalline substance has a single microstate at absolute zero, leading to zero entropy.

A container has hydrogen and oxygen mixture in ratio of 4 : 1 by weight, then

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Explanation

When hydrogen and oxygen are mixed, the number of possible microstates increases, leading to an increase in entropy. Entropy is a measure of disorder, and mixing two different gases increases the disorder of the system.

The second law of thermodynamics says that in cyclic process.

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Explanation

The second law of thermodynamics states that heat cannot be completely converted into work in a cyclic process. There will always be some waste heat that is not converted into work, which is why perpetual motion machines of the second kind are impossible.

A heat engine absorbs heat $Q_1$ at temperature $T_1$ and heat $Q_2$ at temperature $T_2$. Work done by the engine is $(Q_1 + Q_2)$ . This data

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The molar neutralization heat for and as compared to molar neutralization heat of NaOH and HCl

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Explanation

The molar heat of neutralization is the heat change that occurs when one mole of water is formed from the reaction of an acid and a base. For strong acids and bases like NaOH and HCl, the molar heat of neutralization is typically constant at about -57.1 kJ/mol because they fully dissociate in water. Thus, the molar neutralization heat is equal for strong acid and base combinations.

If the enthalpy of B is greater than of A, the reaction $ A \rightarrow B $ is

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Explanation

An endothermic reaction is one that absorbs energy from its surroundings, typically in the form of heat. If the enthalpy of B is greater than that of A, it means the reaction $A ightarrow B$ requires an input of energy, making it an endothermic reaction.

Which of the following fuels will have the highest calorific value (kJ/kg)

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Explanation

Kerosene has a higher calorific value compared to charcoal, wood, and dung. Calorific value is the amount of energy released during the combustion of a substance. Kerosene, being a refined petroleum product, has a higher energy content per kilogram compared to the other options.

Which is the best definition of “heat of neutralization”

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Explanation

The heat of neutralization is defined as the heat set free when one gram equivalent of an acid is neutralized by one gram equivalent of a base in dilute solution at a stated temperature. This definition specifically considers the neutralization reaction between acid and base in molar equivalents.

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