Chemistry · Science General

Common Chemical Compounds and Reactions

1,197 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

Why is common salt added to soap during its production?

  1. To decrease the solubility of the soap

  2. To increase the solubility of the soap

  3. To produce leather with hard water

  4. To provide greater cleaning action
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Common salt (sodium chloride) is added during soap manufacturing to reduce the solubility of soap in water, a process known as salting out. This causes the soap to precipitate and separate cleanly from the aqueous solution.

Multiple choice

Washing soda is used with soap to _______ the water for washing clothes.

  1. harden

  2. increase

  3. clean

  4. soften
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Washing soda (sodium carbonate decahydrate, Na2CO3·10H2O) is a water softener. It reacts with calcium and magnesium ions in hard water, converting them into soluble forms, thus softening the water. Softened water allows soap to lather better and clean clothes more effectively. Hard water reduces soap's cleaning efficiency.

Multiple choice

What chemical is described with the formula KCI?

  1. Lead chloride

  2. Potassium chloride

  3. Phosphorous chloride

  4. Magnesium chloride
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The formula KCI represents potassium chloride (KCl), a salt composed of potassium and chlorine. It's widely used as a fertilizer, in medical treatments for electrolyte imbalances, and as a salt substitute. The chemical notation shows K (potassium) bonded with Cl (chlorine), though sometimes written with a lowercase 'l' appearing as 'I'.

Multiple choice

Soap molecules form __________ with hard water.

  1. lather

  2. scum

  3. precipitate

  4. both 1 and 2

  5. both 2 and 3
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Yes, this is the correct option. With hard water soap solutions form a white precipitate and off white layer over water known as soap scum, instead of producing lather.

Multiple choice

Why are detergents preferred over soap in hard water?

  1. They are free flowing and easily available.

  2. They do not precipitate with calcium or magnesium salts in hard water.

  3. They change the hard water into soft water.

  4. They form scum, which can easily be removed.

  5. They have fresh odour.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, detergents are ammonium or sulphonate salts of carboxylic acids. The charged ends of these compounds do not form precipitates with calcium or magnesium salts in hard water. Hence, detergents retain their cleansing property in hard water.

Multiple choice

What is common salt?

  1. Sodium chloride

  2. Sodium carbonate

  3. Sodium bicarbonate

  4. Sodium phosphate
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice

Methyl phenol, hydrogen peroxide and sulphur dioxide are the most common examples of

  1. antiseptic products

  2. disinfectants

  3. antacids

  4. antihistamines
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Disinfectants are used to kill bacteria. They are used to sterilize instruments, utensils, clothes, floors, sanitary fittings, sputum and excreta. They harm the living tissues and cannot be used on skin. Some examples are phenol, methyl phenol, hydrogen peroxide and sulphur dioxide.

Multiple choice

Anhydrous calcium chloride, quick lime and concentrated sulphuric acid act as

  1. drying agents

  2. cleansing agents

  3. oxidizing agents

  4. reducing agents
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Substances that are capable of taking away moisture from a gas are called drying agents. As all deliquescent and hygroscopic substances have affinity for water, they can be used as drying agents. However, usually anhydrous calcium chloride, quick lime and concentrated sulphuric acid are used as drying agents in the laboratory.