Free s-Block and p-Block Elements MCQs with Answers

• A. HF
• B. HCI
• C. HBr
• D. HI

Explanation: HF is the weakest acid in water among these hydrogen halides because the H-F bond is exceptionally strong and does not break readily.

• A. pale yellow
• B. freenish yellow
• C. reddish brown
• D. grayish black

Explanation: Chlorine gas appears greenish yellow because it absorbs some wavelengths of visible light while transmitting and reflecting the…

• A. Cl2O7
• B. Cl2O6
• C. ClO2
• D. all

Explanation: ClO2 has an odd number of valence electrons, so one electron remains unpaired, making it paramagnetic.

• A. Cl2 is the strongest oxidizing agent
• B. I2 is a volatile solid
• C. Br2 is more reactive than Cl2
• D. Cl2 is insoluble in water

Explanation: Iodine is a volatile solid because its relatively weak intermolecular forces allow it to sublime readily on warming.

• A. AgNO3
• B. AgI
• C. AgCl
• D. AgBr

Explanation: Photographic plates traditionally contain silver bromide, AgBr, in a light-sensitive coating.

• A. SbF3 is used for manufacture of pottery
• B. Sodium fluoroacetate is a rat poison
• C. Cu F2 is used in ceramic industry
• D. None of the above

Explanation: All three listed fluorine compounds have recognized uses: antimony(III) fluoride is used in pottery-related work, sodium fluoroacetate is…

• A. Cotton
• B. Costly fabrics
• C. Linen
• D. Paper pulb

Explanation: Bleaching powder releases chlorine or hypochlorous acid, which oxidizes coloured substances but can damage delicate or costly fabrics.

• A. NaCLO
• B. NaClO2
• C. NaClO3
• D. NaClO4

Explanation: Sodium hypochlorite contains the hypochlorite ion, ClO−, so its formula is NaClO. The oxyanion charge is balanced by one Na+ ion.

• A. Flourine
• B. Chlorine
• C. Iodine
• D. Bromine

Explanation: Fluorine is the strongest oxidizing halogen, so it can oxidize and displace chloride, bromide and iodide ions from their compounds.

• A. Displacement reaction
• B. Double displacement reaction
• C. Disproportionation reaction
• D. Reduction reaction

Explanation: In 3Cl2 + 6NaOH → NaClO3 + 5NaCl + 3H2O, chlorine starts at oxidation state 0 and is simultaneously reduced to -1 in NaCl and oxidized to…

• A. Cl2O
• B. ClO2
• C. Cl2O6
• D. Cl2O7

Explanation: In acidic solution, chlorate ion is reduced to chlorine dioxide, so balancing chlorine atoms gives 2 KClO3 producing 2 ClO2.

• A. Iodine solution
• B. Chlorine
• C. NaCl
• D. Ki

Explanation: Chlorine is more reactive than bromine and oxidises bromide ions: Cl2 + 2KBr -> 2KCl + Br2.

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

Explanation: Chlorine has the highest electron affinity among the halogens because its larger atomic size allows an incoming electron to enter with…

• A. F2
• B. Cl2
• C. Br2
• D. I2

Explanation: Chlorine reacts directly with gold to form gold(III) chloride: 2Au + 3Cl2 -> 2AuCl3.

• A. F2
• B. Cl2
• C. Br2
• D. I2Cleaning Agents

Explanation: F2 is the strongest oxidising agent because fluorine has the greatest tendency to gain electrons and its reduction to F- is highly…

• A. F2
• B. Cl2
• C. Br2
• D. I2

Explanation: Van der Waals forces increase from F2 to I2 because the electron cloud becomes larger and more easily polarised, producing stronger…

• A. Fluorine
• B. Chlorine
• C. Astatine
• D. Iodine

Explanation: Astatine is the rarest naturally occurring halogen because it is radioactive and has no long-lived stable isotope, so only trace amounts…

• A. Alkali
• B. Acid
• C. Water
• D. Metals

Explanation: Oxygen reacts with many metals to form metal oxides, for example 2Mg + O2 -> 2MgO.

• A. Fe
• B. A
• C. Cr
• D. All of the above

Explanation: Concentrated HNO3 passivates Fe, Cr, and Al by forming a thin, protective oxide film on their surfaces, which prevents further reaction.

• A. Yolk of egg
• B. Bone
• C. Nerves
• D. Steel

Explanation: Steel is mainly an alloy of iron and carbon and does not normally contain phosphorus as an essential constituent, whereas phosphorus…