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

Plaster of Paris is technically known as

  1. potassium permanganate

  2. calcium sulphate

  3. hydrated calcium sulphate

  4. calcium carbonate
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plaster of Paris is chemically calcium sulfate hemihydrate (CaSO₄·½H₂O), formed by heating gypsum to remove some water of crystallization. It's called 'hydrated calcium sulphate' because it still contains some water molecules in its crystal structure, unlike anhydrous calcium sulfate. Potassium permanganate and calcium carbonate are entirely different compounds with no relation to Plaster of Paris.

Multiple choice

Which of the following statements is/are correct?

(1) Mild hydrochloric acid is used to get relief from bee sting. (2) Plaster of Paris is mainly an organic compound of calcium.

  1. Only (1)

  2. Only (2)

  3. Both (1) and (2)

  4. Neither (1) nor (2)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Statement 1 is wrong. A basic compound (like baking soda) is used to neutralise the effect of bee sting, which produces formic acid. Statement 2 is correct. Plaster of Paris is mainly an organic compound of calcium. It is basically calcium sulphate.

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

Sunflower contains

  1. cobalt chloride

  2. calcium chloride

  3. sodium chloride

  4. cobalt nitrate
Reveal answer Fill a bubble to check yourself
A Correct answer
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'.