All Free Chemistry MCQs with Answers

• A. O
• B. S
• C. Cd
• D. Fe

Explanation: Valence electrons are the electrons in the outermost shell of an atom. Sulfur (S) is in group 16 of the periodic table, which means it has…

• A. NaCl
• B. NaNO₃
• C. NaOH
• D. NaNO₄

Explanation: Chile saltpeter is the common name for sodium nitrate (NaNO₃). It is a naturally occurring mineral that is found in large deposits in…

• A. XeF₂
• B. XeF₄
• C. XeF₆
• D. All of the above

Explanation: Hydrofluoric acid (HF) can be produced by the reduction of all the given xenon fluorides (XeF₂, XeF₄, XeF₆).

• A. Oxidizing
• B. Reducing
• C. Both a and b
• D. None of these

Explanation: Bleaching powder, chemically known as Calcium Oxychloride (CaOCl₂), is an oxidizing agent.

• A. Ca(ClO)₄
• B. Ca₂(ClO)₂
• C. Ca(ClO)₂
• D. Ca(Cl₂O)₂

Explanation: Bleaching powder, also known as calcium hypochlorite, has the chemical formula Ca(ClO)₂.

• A. Bromine
• B. Fluorine
• C. Chlorine
• D. Argon

Explanation: Tear gas is a chemical irritant that causes a burning sensation in the eyes, leading to tears and discomfort.

• A. F
• B. Cl
• C. Br
• D. I

Explanation: Fluorine (F) is used in the production of various refrigerants, particularly in the form of chlorofluorocarbons (CFCs) and…

• A. Radon
• B. Neon
• C. Argon
• D. Both a and b

Explanation: Argon (Ar) is a noble gas that is used in various applications due to its inert nature.

• A. 1.77 kJ/mol
• B. 9.7 kJ/mol
• C. 18.0 kJ/mol
• D. 6.5 kJ/mol

Explanation: This means that to vaporize one mole of liquid radon, 18.0 kilo joules of energy are required.

• A. Cl
• B. I
• C. Br
• D. F

Explanation: Fluorine (F) is the most electronegative element and does not form stable oxyacids. It is too reactive to form stable bonds with oxygen.

• A. F₂>Br₂>Cl₂>I₂
• B. F₂>Cl₂>Br₂>I₂
• C. F₂<Cl₂<Br₂<I₂
• D. F₂<Br₂<Cl₂<I₂

Explanation: Oxidizing power refers to the ability of a substance to gain electrons and oxidize another substance.

• A. KMnO₄
• B. K₂MnO
• C. KMnO₂
• D. None of these

Explanation: The correct formula for Potassium permanganate is KMnO₄

• A. He
• B. Ne
• C. Ar
• D. Kr

Explanation: The boiling point of noble gases increases down the group. Krypton (Kr) has the highest boiling point among the given noble gases.

• A. F to At
• B. N to Bi
• C. C to Sn
• D. H to Cs

Explanation: Halogens are a group of non-metallic elements that are located in Group 17 of the periodic table.

• A. XeF₆
• B. XeF₄
• C. XeF₂
• D. All of these

Explanation: Xenon fluorides (XeF₂, XeF₄, and XeF₆) are used as precursors to synthesize various xenon oxides.

• A. 5-10
• B. 20-25
• C. 35-40
• D. 90

Explanation: Bleaching powder, also known as calcium hypochlorite (Ca(ClO)₂), typically contains a percentage of available chlorine in the range of…

• A. Cryolite
• B. Fluorspar
• C. Dolomite
• D. Both a and b

Explanation: Both Cryolite (Na₃AlF₆) and Fluorspar (CaF₂) are important ores of fluorine.

• A. Strong oxidizing agent
• B. Weak oxidizing agent
• C. Strong reducing agent
• D. Weak reducing agent

Explanation: Sulfur (S) acts as a strong reducing agent in the reaction with HI. This is because sulfur has a higher tendency to lose electrons (get…

• A. High ionization energy
• B. Low ionization energy
• C. Zero ionization Energy
• D. None of these

Explanation: Noble gases have a very high ionization energy. This is because their outermost electron shell is completely filled, making them very…

• A. F₂
• B. Cl₂
• C. Br₂
• D. I₂

Explanation: The oxidizing power of halogens decreases down the group. Fluorine (F₂) is the strongest oxidizing agent among the halogens, followed by…