All Free Chemistry MCQs with Answers
Every Chemistry question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
13,720 questions · page 526 of 686
- A. ∆H = O
- B. ∆H > ∆E
- C. ∆H = ∆E
- D. ∆H < ∆E
Explanation: In summary, the correct statement is "c) ∆H = ∆E" because, for this reaction, the change in enthalpy (∆H) is equal to the change in…
Correct answer: ∆H = ∆E10502. If work done on a system is 650) and heat taken out from the system is 500J, the change in internal?
- A. -1150
- B. +1150
- C. +150
- D. -150
Explanation: The change in internal energy is given by the equation:∆E = q - w,where q is the heat transferred to the system and w is the work done by…
Correct answer: +150- A. Potential energy
- B. Kinetic energy
- C. Electric energy
- D. Heat energy
Explanation: The energy possessed by water in a dam is potential energy.Potential energy is the energy that an object has due to its position or state.
Correct answer: Potential energy- A. Reversible
- B. Mechanical
- C. Exothermic
- D. Endothermic
Explanation: The process is endothermic.Endothermic processes are those in which heat is absorbed from the surrounding.
Correct answer: Endothermic- A. It is an exothermic process
- B. Formation of water is a spontaneous process
- C. It is the heat evolved for complete reaction of 2 moles of oxygen with excess of hydrogen
- D. Water is at lower energy than its reactants
Explanation: The enthalpy change (∆H) is negative, which means that heat is absorbed from the surroundings during the formation of water.
Correct answer: It is an exothermic process- A. For liquids
- B. for solids
- C. for Any in gas phase rex
- D. For gas phase rex. having greater no. of moles of product.
Explanation: The answer is for gas phase reactions having greater number of moles of products.The enthalpy change (∆H) and the internal energy change…
Correct answer: For gas phase rex. having greater no. of moles of product.- A. q1 + q2
- B. q1 - q2
- C. q2 - q1
- D. -q1 - q2
Explanation: The enthalpy change for the reaction CH3COOH → CH3COO- + H is the difference between the enthalpy change for the first reaction and the…
Correct answer: q1 - q2- A. lonization energy
- B. Electron affinity
- C. Combustion
- D. Exothermic reaction
Explanation: The answer is ionization energy.Ionization energy is the energy required to remove an electron from an atom or molecule in the gaseous…
Correct answer: lonization energy- A. H2 + l2 ➞ 2HI
- B. 2H2O2➞2H2O+O2
- C. PCI5 ➞ PCI3+Cl2
- D. C+O2 ➞ CO2
Explanation: The change in enthalpy is equal to the change in internal energy for reaction 1, H2 + I2 ➞ 2HI as ∆ n = 0
Correct answer: H2 + l2 ➞ 2HI- A. The change in heat content
- B. The total energy change at constant pressure and temperature
- C. The heat change at constant volume if ∆n=0
- D. Work done at constant pressure
Explanation: The change in enthalpy is defined as the total energy change at constant pressure and temperature.
Correct answer: The total energy change at constant pressure and temperature- A. Thermochemistry
- B. Electrochemistry
- C. Nuclear chemistry
- D. Chemical kinetics
Explanation: The study of heat changes that accompany a chemical reaction is called "Thermochemistry", therefore option A is the correct answer.
Correct answer: Thermochemistry- A. It indicates physical state of reactants and products
- B. It indicates whether the reaction is exothermic or endothermic
- C. It indicates allotropes of the reactants if present
- D. It indicates whether a reaction would occur or not
Explanation: The indication of whether a reaction would occur or not is not a characteristic of a thermochemical equation.Thermochemical equations only…
Correct answer: It indicates whether a reaction would occur or not- A. The heat liberated during the neutralization of a strong acid and a strong base in aqueous solution is constant
- B. The heat of combustion is always an exothermic change
- C. The enthalpies of the formation of carbon dioxide can be conveniently determined if the heat of combustion data of carbon is given
- D. The heat of formation of a compound is equal in magnitude to the heat of combustion
Explanation: The statement is not true. The heat of formation and the heat of combustion are two different thermodynamicquantities related to chemical…
Correct answer: The heat of formation of a compound is equal in magnitude to the heat of combustion- A. Graphite is chemically different from diamond
- B. Graphite is as stable as diamond
- C. Graphite is more stable than diamond
- D. Diamond is more stable than graphite
Explanation: The negative value of ∆H (-1.9 kJ) for the transition of carbon from diamond to graphite indicates that the process is exothermic and that…
Correct answer: Graphite is more stable than diamond- A. decreases
- B. remains constant
- C. increases
- D. None of the above
Explanation: Option A is correct because the solution temperature would decrease as there would be more substances absorbing the heat.
Correct answer: decreases- A. Joule
- B. Kelvin
- C. Calorie
- D. Kilo joule (KJ)
Explanation: Option B is correct because Kelvin is the unit that only measures temperature.
Correct answer: Kelvin- A. Universe
- B. Boundary
- C. System
- D. Surrounding
Explanation: Option C is correct because anything that is under observation is called a system because whatever is in it is carefully observed and…
Correct answer: System- A. 163.32 kj/mol
- B. 32.64 kj/mol
- C. 326.4 KJ/mol
- D. 3.264 kJ/mol
Explanation: To calculate the energy evolved when 7.8 g of benzene (C6H6) is burnt in air, we need to use the given enthalpy change (∆H) and the molar…
Correct answer: 326.4 KJ/mol- A. Conditions of P or V under which a reaction is carried out
- B. Initial and final enthalpies of the reactants and products
- C. State of reactants and products
- D. Number of intermediate stages involved
Explanation: Option D is correct because enthalpy is a state function. So, enthalpy change does not depend upon the different steps involved in the…
Correct answer: Number of intermediate stages involved- A. HCI(g) ➞ H(g) + Cl(g)
- B. HCL(g) ➞ 1/2 H2(g) + 1/2 - CI2(g)
- C. 2HCI(g) H2(g) + CI2(g)
- D. HCI(g) -H(g) +CI-(g)
Explanation: "The explanation for this question will be added soon!".
Correct answer: HCI(g) ➞ H(g) + Cl(g)