Chemistry · Science General

Common Chemical Compounds and Reactions

1,204 Questions

Common chemical compounds and reactions questions test your knowledge of everyday chemicals, their formulas, and their interactions. Topics include properties of acids and bases, hard water chemistry, and compounds like baking soda and plaster of paris. This section is essential for general science preparation.

Acids and basesPlaster of parisHard water chemistryCommon chemical formulasEveryday chemical reactions

Common Chemical Compounds and Reactions Questions

Multiple choice
  1. Both chalk powder and salt will be completely dissolved making the water milky.

  2. Chalk powder will first float, then settle down at the bottom and the salt will be fully dissolved.

  3. Both salt and chalk powder will be undissolved.

  4. Chalk powder will completely dissolve and salt will remain undissolved on the surface.

  5. NA

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The same is correct because chalk powder will first float, then settle down at the bottom and the salt will be fully dissolved.

Multiple choice
  1. cleaning agent

  2. drug

  3. soap

  4. catalyst

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A detergent is a cleaning agent that works by reducing surface tension and emulsifying oils, allowing water to wash away dirt and grease. Unlike soap (which is a specific type of detergent made from fats), detergents are synthetic compounds that work effectively in hard water.

Multiple choice
  1. calcium carbonate

  2. sodium carbonate

  3. calcium bicarbonate

  4. sodium bicarbonate

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Washing soda is the common name for sodium carbonate decahydrate (Na2CO3·10H2O). It's called "washing" soda because it's widely used as a water softener in laundry and cleaning products. Sodium carbonate alone (anhydrous) is soda ash.

Multiple choice
  1. By dissolving solid in water

  2. By observing the size of particles

  3. By sieving

  4. By heating

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chalk powder is insoluble in water while salt completely dissolves, so adding water to each substance will clearly differentiate them - the chalk powder will remain as a solid residue at the bottom while salt will disappear into the water. Particle size observation and sieving won't work reliably since both can have similar particle sizes, and heating would just evaporate water from salt but leave both as solids.

Multiple choice
  1. Salt

  2. Sugar

  3. Baking powder

  4. Chalk powder

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Salt (NaCl) dissolves fastest in water because it's an ionic compound that readily dissociates into Na+ and Cl- ions when in contact with water. Sugar takes longer to dissolve, baking powder is a mixture that reacts before fully dissolving, and chalk powder is mostly insoluble in water. The ionic nature of salt makes it highly soluble with quick dissolution kinetics.

Multiple choice
  1. Potassium Chlorate

  2. Phosphorous pentoxide

  3. Potassium Chloride

  4. All the above

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The head of a safety match contains an oxidizing agent, typically potassium chlorate (KClO3), which provides oxygen to sustain combustion when the match is struck. Phosphorus pentoxide (P2O5) is not used on match heads. Potassium chloride (KCl) is different from potassium chlorate.

Multiple choice
  1. Potassium Chlorate

  2. Potassium Chloride

  3. Antimony Trisulphide

  4. Red phosphorus

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a safety match, the striking surface contains red phosphorus. When the match is struck, friction converts red phosphorus to white phosphorus, which ignites and initiates the combustion of potassium chlorate and antimony trisulfide on the match head. Red phosphorus on the side surface ignites FIRST, then transfers heat to the match head.

Multiple choice
  1. (III) and (IV)

  2. (II) and (III)

  3. (I), (II). (III) and (IV)

  4. (I) and (IV)

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Safety match heads contain antimony trisulfide (the fuel), potassium chlorate (the oxidizing agent), and powdered glass (abrasive). The striking surface contains red phosphorus. When the match is struck, friction generates heat, the red phosphorus converts to white phosphorus, which ignites the potassium chlorate, starting the combustion of antimony trisulfide.

Multiple choice
  1. Sulphur

  2. Oxygen

  3. Chlorine

  4. Phosphorus

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Phosphorus (specifically red or white phosphorus) is used in matchbox industries, particularly on the striking surface of safety matches. When the match head is rubbed against this surface, the friction generates enough heat to ignite the phosphorus, which then ignites the match head. Sulphur is sometimes present in the match head itself, but the key material on the striking surface is phosphorus.

Multiple choice
  1. Jeweller's borax: Na2B4O7.10H2O

  2. Fool's gold: FeS2

  3. Gymnastic’s chalk: MgCO3

  4. Photographer’s hypo: Na2S2O3.5H2O

  5. Baker's ammonia: (NH4)2CO3

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Jeweller's borax (Na2B4O7. 5H2O) is the borax,  which contains five molecules of water of crystallisation.