Chemistry 9th Chap 8 : Topic 1 - Maryam Publications

Chemistry Chapter 8 : Topic 1

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A student performs a reaction in a sealed flask placed in a water bath. The reacting chemicals inside the flask are referred to as the system, while everything outside the flask (water bath, air, thermometer) is considered surroundings. Which statement best explains this classification?

A) Surroundings are only the container, while system is everything inside the laboratory

B) System includes everything involved in measurement, while surroundings include only the flask

C) System and surroundings are the same because both participate in energy exchange

D) System is the part under study, and surroundings are everything external that can interact with it

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A chemical reaction occurs in an open beaker, and heat is released to the surrounding air causing the temperature of the room to increase. Which statement correctly describes the energy transfer?

A) No energy is transferred because the system is open

B) Energy is destroyed during the reaction

C) Energy flows from system to surroundings, making it exothermic

D) Energy flows from surroundings to system, making it endothermic

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A student observes that when ammonium nitrate dissolves in water, the container becomes cold. Which interpretation is most accurate?

A) The system absorbed heat from surroundings (endothermic process)

B) No heat exchange occurred

C) The system released heat to surroundings (exothermic process)

D) The container absorbed chemical energy permanently

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In a chemical reaction, the total energy of reactants is higher than that of products. What can be concluded about the system?

A) Energy is released to surroundings

B) Reaction cannot occur spontaneously

C) Energy remains constant in system only

D) Energy is absorbed from surroundings

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Which statement best explains the concept of “universe” in chemical thermodynamics?

A) Only the external environment around reaction

B) System plus surroundings considered together

C) Only gases involved in reaction

D) Only the reacting substances in a container

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A reaction is carried out in an insulated container so that no heat is lost or gained from surroundings. What type of system is this?

A) Closed system

B) Isolated system

C) Open system

D) Mechanical system

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During bond breaking in reactants, energy is absorbed, while bond formation releases energy. If more energy is released than absorbed, what is the net result?

A) Exothermic reaction

B) Energy remains stored in bonds only

C) Endothermic reaction

D) No reaction occurs

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Which of the following best explains why surroundings become hotter in an exothermic reaction?

A) System absorbs heat from surroundings

B) No heat transfer occurs

C) System releases heat to surroundings

D) Surroundings release heat to system

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A chemical system absorbs 50 kJ of energy from surroundings. What happens to the surroundings?

A) They lose energy

B) They remain unchanged

C) They gain energy

D) Energy is created in surroundings

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In which case is the system correctly defined?

A) Ice melting in a glass: system is air only

B) Boiling water: system is room temperature air

C) Burning fuel: system is fuel and oxygen involved in reaction

D) Rusting iron: system is only oxygen in air

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A reaction is performed in a calorimeter and temperature of water increases. What does this indicate?

A) Reaction is incomplete

B) Endothermic reaction absorbing heat

C) Exothermic reaction releasing heat

D) No heat exchange occurred

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Why is energy transfer important in chemical reactions?

A) It determines color change only

B) It helps identify whether reaction is physical or chemical

C) It shows whether a reaction is exothermic or endothermic

D) It prevents reactions from occurring

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A system is said to be “closed” when:

A) It exchanges neither matter nor energy

B) It exchanges both matter and energy

C) It exchanges matter but not energy

D) It exchanges energy but not matter

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Which statement correctly describes energy flow during endothermic reactions?

A) System releases energy to surroundings

B) Surroundings absorb energy from system

C) System absorbs energy from surroundings

D) No energy transfer occurs

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In a chemical reaction, if surroundings become colder, what is the correct interpretation?

A) System is isolated

B) No energy is involved

C) Reaction is endothermic

D) Reaction is exothermic

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Which of the following is the best example of an open system?

A) Boiling water in an open beaker

B) Ice in a closed container

C) Sealed bottle of soda

D) Thermos flask

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The law of conservation of energy in chemical reactions implies that:

A) Energy is destroyed in reactions

B) Energy is created during reactions

C) Energy only changes form, not created or destroyed

D) Energy remains only in system

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Which factor best explains why energy changes occur during chemical reactions?

A) Change in physical state only

B) Change in number of atoms only

C) Change in container shape

D) Breaking and forming of chemical bonds

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A reaction occurs in a perfectly insulated container. Which statement is true?

A) Matter is exchanged continuously

B) No heat exchange occurs with surroundings

C) Energy is exchanged with surroundings freely

D) System cannot undergo reaction

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If a reaction releases energy slowly over time to surroundings, what will be observed?

A) No temperature change

B) Sudden temperature drop

C) System becomes massless

D) Gradual increase in surrounding temperature

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