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 528 of 686
- A. Q
- B. Q - W
- C. Q / W
- D. Q + Q
Explanation: The correct answer is Q - W, which corresponds to the change in internal energy (∆E) of a system.
Correct answer: Q - W- A. ∆Hfusion is positive only
- B. ∆H aq is positive only
- C. ∆Hn is negative only
- D. ∆Hsoln is negative only
Explanation: The enthalpy of solution (∆Hsoln) can be either positive or negative. It is incorrect to state it is negative only, as dissolution can be…
Correct answer: ∆Hsoln is negative only- A. -217.4 kJ
- B. -119 kJ
- C. +217.4 kJ
- D. +119 kJ
Explanation: To find the heat of formation of PCl5, we need to add the enthalpy changes of the given reactions.
Correct answer: +119 kJ- A. (y - 2x)
- B. (x + y)
- C. (2x -y)
- D. 2x/y
Explanation: Reverse the second reaction and change the sign of its enthalpy change: SO3(g) + y kJ → SO2(g) + 1/2 O2(g) Multiply the first reaction by…
Correct answer: (2x -y)- A. 4
- B. 27
- C. 4/27
- D. 1/27
Explanation: To find the equilibrium constant Kp for the reaction NH4COONH2(s) <-> 2NH3(g) + CO2(g), we use the formula Kp = PNH3^2 * PCO2 where P…
Correct answer: 4- A. Tf > Ti for reversible process but Tf = Ti for irreversible process.
- B. (Tf)rev = (Tf)irrev
- C. Tf = Ti for both reversible and irreversible processes
- D. (Tf)irrev > (Tf)rev
Explanation: In an isolated system, the expansion of an ideal gas occurs adiabatically, meaning no heat is exchanged with the surroundings (q = 0).
Correct answer: (Tf)irrev > (Tf)rev- A. the internal energy changes in all processes
- B. internal energy and entropy are state functions
- C. the change in entropy can never be 0
- D. the work done an adiabatic process is always 0
Explanation: This statement is generally true. State functions depend only on the current state of a system (its thermodynamic state), not on the path…
Correct answer: internal energy and entropy are state functions- A. Entropy
- B. Internal energy
- C. Volume
- D. Density
Explanation: Density is not a state variable of thermodynamics because it depends on both the state variables of volume and mass.
Correct answer: Density- A. Amount of heat added to the system
- B. Amount of heat rejected from the system
- C. The temperature of the substance
- D. Amount of the substance
Explanation: The change in entropy is defined as ΔS = ΔQ/T, where ΔQ is the heat transfer and T is the temperature.
Correct answer: Amount of the substance- A. Decreases
- B. Increases
- C. Remains the same
- D. Both A and B
Explanation: The energy of the universe increases because energy never flows uphill spontaneously.
Correct answer: Increases10551. Which is intensive property?
- A. Boiling point
- B. Molarity
- C. Freezing point
- D. All of the above
Explanation: An intensive property does not change with the size or amount of the sample; it is inherent to the substance itself.
Correct answer: All of the above- A. Double of the original value
- B. Half of the original value
- C. Remain the same as the original value
- D. One-fourth of the original value
- E. Heat of formation
Explanation: Thermodynamic properties can be divided into two general classes, intensive and extensive properties.
Correct answer: Half of the original value- A. Temperature
- B. Volume
- C. Quantity
- D. Pressure
Explanation: Mass and volume are examples of extensive properties. An intensive property is a property of matter that depends only on the type of…
Correct answer: Quantity- A. 2
- B. 6
- C. 4
- D. 8
Explanation: The coordination number of a transition metal complex is defined as the number of ligands attached to the central metal atom/ion.
Correct answer: 6- A. 0
- B. 2
- C. 4
- D. 6
Explanation: CO is a neutral monodentate ligand. The charge on the overall complex is zero.
Correct answer: 0- A. outer transition elements
- B. inner transition elements
- C. typical transition elements
- D. Transition elements
Explanation: Transition elements are those elements that have partially filled d orbitals in their ground state or common oxidation states.
Correct answer: Transition elements- A. increases
- B. decreases
- C. remain same
- D. no regular trend
Explanation: This is generally correct. As you move across the 3d series from left to right, there is an increase in the atomic number.
Correct answer: increases- A. orbitals of f sub shell
- B. orbitals of d sub shell
- C. both a and b
- D. Orbitals of p-subshell
Explanation: Transition elements are characterized by the partially filled d-subshell in their electronic configuration.
Correct answer: both a and b- A. anion
- B. cation
- C. ligand
- D. acid
Explanation: Ligands are molecules or ions that donate electrons to a central metal atom to form a coordination complex.
Correct answer: ligand- A. Ammine
- B. oxalato
- C. carbonyl
- D. cyano
Explanation: A chelate is a complex in which a central metal ion is bonded to the same ligand at multiple points.The oxalate ion (C₂O₄²⁻) has two…
Correct answer: oxalato