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Chemistry NEET Questions — Free MCQ Practice

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Which one of the following statement is falseâ€“

A. work is a state function B. temperature is a state function C. change in the state is completely defined when the initial and final states are specified D. work appears at the boundary of the system.

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Explanation

Work is not a state function. Work depends on the path taken to reach one state from another, not just the initial and final states. Therefore, it is path-dependent. On the other hand, state functions like temperature, pressure, and volume depend only on the state of the system and not on how that state was achieved.

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A mixture of two moles of carbon monoxide and one mole of oxygen, in a closed vessel is ignited to convert the carbon monoxide to carbon dioxide. If OH is the enthalpy change and OE is the change in internal energy, then

A. $OH \lt OE $ B. $ OH \gt OE $ C. OH = OE D. The relationship depends on the capacity of the vessel

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Explanation

In an exothermic reaction like the combustion of carbon monoxide to carbon dioxide, the enthalpy change (Î”H) is typically greater than the change in internal energy (Î”E). This is because Î”H accounts for the heat released to the surroundings at constant pressure, which includes the work done by the system due to volume change. The relationship can be expressed as Î”H = Î”E + PÎ”V, where PÎ”V is the work done by the system. Since gases are involved, PÎ”V is positive, making Î”H greater than Î”E.

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At constant T and P, which one of the following statements is correct for the reaction, $ CO_{(g)} + { 1 \over 2 } O_{2(g) } \rightarrow CO_{2(g) } $

A. OH is independent of the physical state of the reactants of that compound ( B. $ OH \lt OE $ C. $ OH \gt OE $ D. OH = OE

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Explanation

For the reaction $CO_{(g)} + {1 ackslash 2} O_{2(g)} ightarrow CO_{2(g)}$, the enthalpy change (Î”H) is greater than the change in internal energy (Î”E) because the reaction involves a change in the number of moles of gas. At constant temperature and pressure, the enthalpy change includes the pressure-volume work done by the system, making Î”H larger than Î”E.

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If $ \triangle H $ is the change in enthalpy and the changes in internal energy accompanying a gaseous reaction

A. $ \triangle H $ is always greater than $ \triangle E $ B. $ \triangle H \lt \triangle E $ only if the number of moles of the products is greater than the number of the reactants C. $ \triangle H $ is lways less than $ \triangle E $ D. $ \triangle H \lt \triangle E $ only if the number of moles of the products is less than the number of moles of the reactants

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Explanation

The change in enthalpy (Î”H) can be less than the change in internal energy (Î”E) if the number of moles of the products is less than the number of moles of the reactants. This is because Î”H = Î”E + PÎ”V, and if the volume decreases (fewer moles of gas), then PÎ”V is negative, making Î”H less than Î”E.

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Enthalpy is an ________property

A. Extensive B. Exclusive C. Intensive D. Inclusive

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Explanation

Enthalpy is an extensive property. Extensive properties depend on the amount of matter in a sample. Since enthalpy is proportional to the amount of substance, it is classified as an extensive property.

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Select the correct set of statements/s : I . Work done by the surrounding in case of infinite stage expansion is more than single stage expansion II . Irreversible work is always greater than reversible work III . On an ideal gas in case of single stage expansion and compression system as well as surrounding are restored back to their original states IV . If gas is in thermodynamic equilibrium is taken from state A to state B , by four successive single stage expansions,. Then we can plot 4 points on the P-V indicator diagram

A. II B. I , II, III , IV C. II , IV D. I , II , IV

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Hess Law of Heat summation includes

A. Initial reactants only B. Initial reactants and final products C. Final products only D. Intermediates only

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Explanation

Hess's Law of Heat Summation states that the total enthalpy change of a reaction is the same, regardless of the number of steps the reaction is carried out in. Thus, it includes both the initial reactants and final products. This implies that the enthalpy change is dependent on the initial and final states of the reactants and products.

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Ice - Water mass ratio is maintained as 1:1 in a given system containing water in equilibrium with ice at constant pressure. If CP (ice) = CP (water) = 4.18 J $mol ^ {-1} K^ {-1} $ molar heat capacity of such a system is

A.

zero

B.

infinity

C.

$ 4.182 JK^ {-1} mol ^ {-1} $

D.

$ 75.48 JK^{-1} mol ^ {-1} $

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During winters , moisture condenses in the form of dew and can be seen on plant leaves and grass. The entropy of the system in such cases decreases as liquids possess lesser disorder as compared to gases. With reference to the second law, which statement is correct , for the above process ?

A. The randomness of the universe decreases B. The randomness of the surroundings decreases C. Increase is randomness of surroundings equals the decrease in randomness of system D. The increase in randomness of the surroundings is greater as compared to the decrease in randomness of the system

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Explanation

As dew formation is spontaneous process therefore entropy or
randomness of the universe will increase. As randomeness of the system has decreased but randomness of the surrounding will increase larger so that change is positive.

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The enthalpy change for a given reaction at $ 298 K is â€“ x J mol^{â€“1} $ (x being positive). If the reaction occurs spontaneously at 298 K, the entropy change at that temperature

A. can be negative but numerically larger than x/298 B. can be negative but numerically smaller than x/298 C. cannot be negative D. cannot be positive

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Explanation

It I is because of the fact that for spontaneity, the value of OG = (OH â€“ TOS) should be $ \lt 0 $ . If OS is â€“ ve, the value of TOS shall have to be less than OH or the value of OS has to be less than that of x

Chemistry MCQs for NEET — Practice Questions with Answers

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