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 545 of 686
- A. Os
- B. Mn
- C. Fe
- D. Po
Explanation: Osmium (Os) is a transition metal belonging to Group 8 (VIII B) of the periodic table and has an atomic number of 76.
Correct answer: Os- A. Metals have free electrons in the valence shell
- B. The electrical conductivity of metals increases with the increase in temperature
- C. Metalloids are poor conductors of electricity
- D. Non-metals have atomic conductance usually less than 10-10 ohm-1
Explanation: Statement B is incorrect because the electrical conductivity of metals decreases with an increase in temperature, not increases.
Correct answer: The electrical conductivity of metals increases with the increase in temperature- A. +2
- B. +1
- C. +3
- D. 0
Explanation: in general, the most common oxidation state of selenium is +2. This is because selenium has six valence electrons and can gain two…
Correct answer: +2- A. [Co(NH3)6]Cl3
- B. [Co(NH3)5Cl]Cl2
- C. [Co(NH3)4Cl2]Cl
- D. [Co(NH3)5.H2O]Cl3
Explanation: This compound has only one ionisable Cl- out of the given three.[Co(NH3)4Cl2]Cl <-> [Co(NH3)4Cl2]+ + Cl-It also exhibits cis-trans isotherm.
Correct answer: [Co(NH3)4Cl2]Cl- A. +7
- B. -7
- C. +6
- D. -6
Explanation: Let x be the oxidation number of Mn. Now, we can set up an equation based on the sum of oxidation numbers: x+(−8)=−2.
Correct answer: +6- A. Aqua
- B. Ammine
- C. Carbonyl
- D. Nitro
Explanation: Nitro (NO2− ) is not a neutral ligand; it is a polyatomic ion with a charge of -1.
Correct answer: Nitro- A. And, Jess
- B. Bragged:
- C. Regardless
- D. Ten
Explanation: The correct answer is B) Bragged.Corrected Sentence: "And, Jess," he bragged, "regardless of my threescore years and ten, I ploughed…
Correct answer: Bragged:- A. Repulse
- B. Summoned
- C. Surfeit
- D. Dismissed
Explanation: To beckon is to motion or gesture someone to approach you. summon is to order someone to be present.
Correct answer: Summoned- A. 120
- B. 174
- C. 128
- D. 175
Explanation: To solve the sequence 180, 140, 179, 138, 177, 134, ?, separate the terms by their positions:Odd-position terms: 180, 179…
Correct answer: 174- A. A. If statement I is the cause and statement II is its effect;
- B. B. If statement II is the cause and statement I is its effect;
- C. C. If both the statements I and II are independent causes;
- D. D. If both the statements I and II are effects of independent causes;
- E. E. If both the statements I and II are effects of some common cause;
Explanation: The correct answer is B. The drop in the tax on petrol imports (statement II) likely caused the government to reduce petrol prices…
Correct answer: B. If statement II is the cause and statement I is its effect;- A. If only I follow
- B. If only II follows
- C. If either I or II follows
- D. If neither I nor II follows
- E. If both I and II follows
Explanation: The explanation for this question will be added soon!
Correct answer: If only II follows- A. Polycyclic hydrocarbons
- B. Mineral acids
- C. D.D.T
- D. Nitrate fertilizers
Explanation: Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds that are formed during incomplete combustion of organic matter…
Correct answer: Polycyclic hydrocarbons- A. H3PO3 is dibasic and reducing
- B. H3PO3 is tribasic and reducing
- C. H3PO3 is tribasic and non-reducing
- D. H3PO3 is dibasic and non-reducing
Explanation: In the structure of H3PO3, two -OH groups are present, so it is dibasic acid.
Correct answer: H3PO3 is dibasic and reducing- A. pH = pKa + log[ Acid/Base ]
- B. pH = pKa - log[ Acid/Base ]
- C. pH = pKa - log[ Base/Acid ]
- D. pH = pKa + log[ Base]
Explanation: The Henderson-Hasselbalch equation relates pKa and pH. However, it is only an approximation and should not be used for concentrated…
Correct answer: pH = pKa - log[ Acid/Base ]- A. NH4+
- B. NH
- C. NH2
- D. NH2-
- E. NH3
Explanation: NH₄⁺: This is the conjugated acid of NH₃ (ammonia). When NH₃ accepts a proton (H⁺), it forms NH₄⁺.
Correct answer: NH4+- A. NO3-
- B. Cl-
- C. SO42-
- D. CH3COO-
Explanation: The strength of a conjugate base is inversely related to the strength of its conjugate acid.
Correct answer: CH3COO-- A. An electron pair
- B. A proton
- C. An electron
- D. Pair of protons
Explanation: The correct answer is that an acid is a substance which accepts an electron pair, according to the Lewis concept.
Correct answer: An electron pair- A. FeCl₃
- B. AlCl₃
- C. BF3
- D. All of these
Explanation: The correct answer is All of these because all the compounds listed (FeCl₃, AlCl₃, and BF3) are Lewis acids.
Correct answer: All of these- A. NH₃
- B. PH₃
- C. RNH₂
- D. R₂NH
Explanation: The correct answer is R₂NH because secondary amines (R₂NH) are generally stronger bases than primary amines (RNH₂) and ammonia (NH₃).
Correct answer: R₂NH10900. The pH of milk is
- A. 5.0
- B. 6.0
- C. 6.2
- D. 6.5
Explanation: The correct pH of milk is around 6.5, indicating it is slightly acidic.
Correct answer: 6.5