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 593 of 686
- A. H2 + I2 ➞ 2HI
- B. 2H2O2 ➞ 2H2O + O2
- C. PCl5 ➞ PCl3 + Cl2
- D. C + O2 ➞ CO2
Explanation: The correct answer is H2 + I2 ➞ 2HI. In this reaction, the change in the number of moles of gas (∆n) is zero, so the change in enthalpy…
Correct answer: H2 + I2 ➞ 2HI- A. The change in heat content
- B. The total energy change at constant pressure
- C. The heat change at constant volume if ∆n=0
- D. Work done at constant pressure
Explanation: Enthalpy change, represented by ΔH, is the total energy change in a system at constant pressure.
Correct answer: The total energy change at constant pressure- A. Joule
- B. Kelvin
- C. Calorie
- D. Kilojoule (kJ)
Explanation: Option B is correct because Kelvin is the unit for measuring temperature, not heat.
Correct answer: Kelvin- A. Universe
- B. Boundary
- C. System
- D. Surroundings
Explanation: The correct answer is Option C: System. In thermochemistry, a system is the specific portion of the universe that is being studied…
Correct answer: System- A. HCl(g) ➞ H(g) + Cl(g)
- B. HCl(g) ➞ 1/2 H2(g) + 1/2 Cl2(g)
- C. 2HCl(g) ➞ H2(g) + Cl2(g)
- D. HCl(g) ➞ H(g) + Cl-(g)
Explanation: The correct answer is Option A:HCl(g) ➞ H(g) + Cl(g). This reaction represents the breaking of the H-Cl bond to form individual hydrogen…
Correct answer: HCl(g) ➞ H(g) + Cl(g)11846. Which is intensive property?
- A. oiling point
- B. Molarity
- C. Freezing point
- D. All
Explanation: An extensive property of a system is that property which depends upon the amount of the substance or substances e.g.
Correct answer: All- A. Tf > Ti for reversible process but Tf = Ti for irreversible process.
- B. (Tf)reversible = (Tf)irreversible
- C. Tf = Ti for both reversible and irreversible processes
- D. (Tf)irreversible > (Tf)reversible
Explanation: During the irreversible expansion of an ideal gas in an isolated system (free expansion), the temperature decreases.
Correct answer: (Tf)irreversible > (Tf)reversible- A. Potassium Tetra Cyano Cupperate
- B. Ligand is positively charged
- C. Coordination Number is 2
- D. Central atom is present in anionic sphere
Explanation: In the complex K2[Cu(CN)4], the central atom is copper (Cu), and it is present in the anionic sphere.
Correct answer: Central atom is present in anionic sphere11849. Pure metal?
- A. corrode slowly
- B. corode rapidly
- C. does not corrode easily
Explanation: This statement is generally true for pure metals. Pure metals have a high degree of chemical stability and are less prone to corrosion…
Correct answer: does not corrode easily- A. simple ions
- B. complex ions
- C. Double salts
- D. strong anion
Explanation: Transition metal compounds can form complex ions in solution by coordinating with surrounding molecules or ions.
Correct answer: complex ions- A. ligand
- B. mono dentate ligand
- C. polydendate ligand
- D. bi dendate ligand
Explanation: This term refers to a ligand that can donate only two pairs of electrons. Why not polydentate ?
Correct answer: ligand- A. Complex Ion
- B. coordination sphere
- C. Ligands
- D. Complex Compounds
Explanation: The coordination sphere includes the central metal atom or ion and its surrounding ligands. It is part of the entire complex compound.
Correct answer: coordination sphere11853. When the central atom of coordination compound is sp3d2 hybridization, the expected geometry will be
- A. tetrahedral
- B. square plannar
- C. trigonal bi pyramidal
- D. octahedral
Explanation: Octahedral geometry is consistent with sp3d2 hybridization. In octahedral geometry, the central atom is surrounded by six ligands arranged…
Correct answer: octahedral11854. Which is sold as fertilizer?
- A. CaSiO3
- B. Fe2O3
- C. Ca3(PO4)2
- D. MnSiO3
Explanation: This compound is calcium phosphate, and it is commonly used as a fertilizer.
Correct answer: Ca3(PO4)2- A. HF (Hydrofluoric acid)
- B. HCl
- C. HBr
- D. HI
Explanation: While HF is the weakest acid in water among the given options, it's important to remember that it's still a highly corrosive and dangerous…
Correct answer: HF (Hydrofluoric acid)- A. ns²p²
- B. ns²p⁴
- C. ns²p⁵
- D. iodine
Explanation: Group VIIA (or Group 17) elements: These elements, also known as halogens, have seven valence electrons in their outermost…
Correct answer: ns²p⁵11857. Which is the strongest acid?
- A. HClO (Hypochlorous acid)
- B. HClO2 (Chlorous acid)
- C. HClO3 (Chloric acid)
- D. HClO4 (Perchloric acid)
Explanation: Strength of Oxyacids of Chlorine:The strength of oxyacids of chlorine generally increases as the number of oxygen atoms attached to the…
Correct answer: HClO4 (Perchloric acid)- A. Displacement reaction
- B. Double displacement reaction
- C. Disproportionation reaction
- D. Reduction reaction
Explanation: What is a disproportionation reaction?It's a type of redox reaction where a single element undergoes both oxidation and reduction…
Correct answer: Disproportionation reaction- A. Fluorine
- B. Chlorine (Cl)
- C. Bromine (Br)
- D. Iodine (I)
Explanation: Fluorine has the highest electronegativity among the halogens. Electronegativity is a measure of an atom's ability to attract electrons in…
Correct answer: Fluorine- A. F2 - fluorine.
- B. Oxidizing power
- C. Halogens and oxidizing power
- D. Relative oxidizing power of halogens
Explanation: Oxidizing power: Oxidizing agents have the ability to accept electrons from other substances, causing them to be oxidized (lose…
Correct answer: F2 - fluorine.