1st Year Chemistry Thermochemistry MCQs with Answers

Here you will get the 1st Year Chemistry Thermochemistry MCQs with Answers. In Chemical Reactions, there are reactions in which heat is evolved or involved. In a chemical reaction, there are spontaneous and non-spontaneous reactions. There are three things in a chemical reaction, System, Surrounding, and State Function. The First Law of Thermodynamics is very valuable. Enthalpy is also a crucial term for Chemical Reactions. Enthalpy can be measured in two ways i.e. Glass Calorimeter and Bomb Calorimeter. Hess’s Law plays an important role in Reactions. The Born-Haber cycle is an important application of Hess’s Law. So, get the important MCQs of Thermochemistry on this page given below.

1st Year Chemistry Thermochemistry MCQs with Answers

KEY POINTS

 

Question#1. Enthalpy of neutralization of strong acids and strong bases have the same values because:

• Neutralization leads to the formation of salt and water
• Strong acids and bases are ionic substances
• Acids always give rise to H⁺ and bases always furnish OH^-1 ions
• The net change involves the combination of H⁺ and OH^-1 ions form water

Question#2. For an endothermic reaction, enthalpy of reactants:

• Is smaller than that of the products
• Is greater than that of the products
• Is equal to that of the products
• Must be greater or smaller than that of the products

Question#3. Which of the following has a positive value of enthalpy:

• Neutralization
• Atomization
  
• Combustion
• All of the above

Question#4. The net heat change in the chemical reaction is the same whether it is brought about in two or more different ways in one or several steps. It is known as:

• Henry’s law
• Hess’s law
• Joule’s principal
• Law of conservation of energy

Question#5. Hess’s law is analogous to:

• Law of heat summation
• Law of increasing entropy
• Law of heat exchange
• 1^st law of thermodynamics

Question#6. NaOH + HCl   →   NaCl + H₂O
Enthalpy change in the above reaction is called:

• Enthalpy of reaction
• Enthalpy of neutralization
• Enthalpy of formation
• Enthalpy of combustion

Question#7. A hypothetical reaction X → 2Yproceeds by the following sequence of steps:
1/2X → Z   ∆H = q₁
Z → 2W     ∆H = q₂
W → 1/2Y   ∆H = q₃
The values for the ∆H of the reaction is:

• q₁ + q₂ + q₃
• 2(q₁ + q₂ + q₃)
• 2q₁ + 2q₂ + 3q₃
• 2(q₁ + q₂ + q₃)

Question#8. Calories are equivalent to:

• 0.4184 J
• 40.18 J
• 4.184 J
• 418.4 J

Question#9. The values of ∆H for the process I_(g) + e^-1  → I^-1_(g) is:

• > 0
• 0
• < 0
• None of the above

Question#10. The enthalpy of formation of a compound is:

• Positive
• Either positive or negative
• Negative
• None of the above

Question#11. What is correct about the heat of combustion:

• It is positive in some cases while negative in other
• It is applicable to gaseous substances only
• It is always negative
• It is always positive

Question#12. What is not correct about ∆H_f?

• Its value gives an idea about the relative stability of reactants and the products
• It is always negative
• Values depend upon the nature of bonds
• Its value can be greater or less than zero

Question#13. If an endothermic reaction is allowed to take place very rapidly in air, the temperature of the surrounding air will?

• Remains constant
• Decrease
  
• Increase
• Either increase or decrease

Question#14. When a solid melts, there is:

• Increase in entropy
• The decrease in internal energy
• Increase in enthalpy
• Both a and b

Question#15. The heat of reaction depends upon:

• The temperature of the reactants
• Physical states of the reactants and the products
• Both a and b
• Path of the reaction and the temperature

Question#16. The exothermic process is:

• Evaporation
• Respiration
• Sublimation
• Boiling

Question#17. During an exothermic or endothermic reaction which one of the following formulae is used to calculate the amount of heat evolved or absorbed_____.

• ∆H = ∆E + PV
• ∆p = ∆H
• ∆E = q + w
• q = m x s x ∆T

Question#18. Most of the reactions which give stable products are:

• Endothermic
• Isothermal
• Exothermic
• None of these

Question#19. The measurement of enthalpy change at standard conditions means that we should manage the measurement that______.

• 24°C at 1 atm
• 0°C at 1 atm
• 25°C at 1 atm
• 100°C 1 at atm

Question#20. The total heat content of a system is called_______.

• Internal energy
• Enthalpy
• Entropy
• All of these

Question#21. The enthalpies of all elements in their standard states are:

• Unity
• Always +ve
• Always –ve
• Zero

Question#22. A state function which describes together the internal energy and product of pressure and volume is called_______.

• Enthalpy
• Internal energy
• Work
• Kinetic energy

Question#23. The enthalpy change for the reaction C₂H₂ + 5/2 O₂ → 2CO₂ + H₂O is brown as enthalpy of:

• Formation of CO₂
• Combustion of C₂H₂
• Fusion of C₂H₂
• Vaporization of C₂H₂

Question#24. The value of ∆V is very small. The term P∆V can be neglected for the process involving:

• Liquid and gas
• Liquid and solid
• Solid and gases
• None of these

Question#25. The lattice energy of NaCl is:

• 787 J/mole
• 780 kJ/mol
• 790 kJ/mol
• -787 kJ/mole

Question#26. Decomposition of H₂O is:

• Endothermic reaction
• Exothermic reaction
• Nuclear reaction
• Zero nuclear reaction

Question#27. According to Hess’s Law, the enthalpy change for a reaction:

• Depends on path
• The sum of ∆E and ∆H
• Independent of the path
• None of these

Question#28. Enthalpy of formation of one mole of an ionic compound from gaseous ion under standard condition is called______.

• Gibb’s energy
• Lattice energy
• Bond energy
• All of these

Question#29. Choose from the following the correct statement about Born Harbor cycle:

• Born Harbor cycle is different from Hess’s law
• The energy changes in a cyclic process is not zero
• The lattice energy of crystalline substances can be calculated easily
• None of these

Question#30. Change in enthalpy of ∆H a system can be calculated by the following relationship:

• ∆H = ∆E-PV
• ∆H = ∆E-Q
• ∆H = ∆E+q
• ∆H = ∆E+P∆V