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 chemistry materials we use soap and detergents soap soap and detergent

Soaps cannot be used in hard water because they:

  1. contain sodium

  2. form precipitates

  3. create environmental problems

  4. create ozone depletion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Soaps cannot be used in hard water because they forms precipitates. When soaps are used in hard water that contains a lot of calcium and magnesium ions they cause the soap to precipitate and it is unable to form lather. This can be minimized by the addition of chemicals like sodium trimetaphosphate, borax, sodium silicate etc. These prevent the calcium and magnesium ions from reacting with the soap and allow it to form lather, thus forming precipitates.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Which of the following statement is not correct ? 

  1. KCI is a substitute for NaCI for patients of high blood pressure.

  2. KOH is a stronger alkali than NaOH

  3. KOH is used in the manufacture of soft soap.

  4. NaOH is a non-deliquescent white crystalline solid.
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Soaps are sodium salts of :

  1. mineral acids

  2. fatty acids

  3. bases

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

Soap is a salt of fatty acid. These are obtained by treating vegetable or animal oils and fats with strong alkaline solution. Fats and oils are composed of triglycerides,three molecules of fatty acids are attached to a single molecule of glycerol. This alkaline solution often called as lye brings about a chemical reaction known as saponification.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Soaps are:

  1. sodium or potassium salts of higher fatty acid

  2. esters of higher fatty acids

  3. glycerides of fatty acids

  4. hydrides of fatty acids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Soaps are water-soluble sodium or potassium salts of fatty acids. Soaps are made from fats and oils, or their fatty acids, by treating them chemically with a strong alkali. 
$C _{12}H _{35}COONa$ is a good example of soap. 

Hence, option $A$ is correct.
Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Sodium hydroxide is found in:

  1. lime water

  2. milk of magnesia

  3. window cleaner

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

$\bullet$ Lime water has $Ca(OH) _2$

$\bullet$ Milk of magnesia has $Mg(OH) _2$
$\bullet$ Window cleaner has $NH _4OH$
$\bullet$ Soap consists of sodium stearate and $NaOH$.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

A product obtained by mixing caustic soda with vegetable oils is:

  1. acid

  2. base

  3. soap

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

When vegetable oils reacted with caustic soda they produce potassium salt of Carboxylate. (Soap)

$\implies Vegetable\ oil+KOH\longrightarrow \underbrace {R-CO\overset {\circleddash}{O}K} _{soap}$

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Which type of chemical substances is disparlure?

  1. Detergent

  2. Antioxidant

  3. Pheromones

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

Disparlure is a pheromones that attracts insects. Pheromones are an additional form of chemical communication that occurs between rather than within individuals.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Washing soaps produce scum with hard water and not much foam because hard water contains:

  1. chalk and sulphur

  2. many dissolved inorganic salts

  3. many suspended particles

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

Hard water contains salts of calcium and magnesium principally as bicarbonates, chlorides, and sulfates. Ferrous ion may also be present; oxidized to the ferric form. It appears as a reddish brown stain on washed fabrics and enameled surfaces. Water hardness that is caused by calcium bicarbonates is known as temporary, because boiling converts the bicarbonates to the insoluble carbonates; hardness from other salts is called permanent. Calcium and magnesium ions in hard water react with the higher fatty acids off soap to form an insoluble gelatinous curd, thereby causing a waste of the soap.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Soaps are sodium salts of fatty acids, RCOONa; e.g. $C _{17}H _{35}COO^-Na^+$. It gives an insoluble precipitate / layer with 

  1. $Ca^{2+}$ (aq)
  2. $Mg^{2+}$ (aq)

  3. HCl (aq)

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Soaps are sodium salts of fatty acids. It gives an insoluble precipitate/layer with Calcium, Magnesium ions. It also gives an insoluble layer with HCl acid.

As a cleaning agent, soap suffers from two main drawbacks:

  • It does not function well in acidic solutions because of the formation of insoluble fatty acid 
eg, $CH _3(CH _2) _{16}COO^-Na^+(aq) + HCl(aq) \rightarrow CH _3(CH _2) _{16}COOH(s) + Na^+(aq) + Cl^-(aq)$
  • It forms insoluble precipitates with $Ca^{2+}$ and$ Mg^{2+}$ ions present in hard water, forming a scum 
eg, $2CH _3(CH _2) _{16}COO^-Na^+(aq) + Ca^{2+}(aq) \rightarrow [CH _3(CH _2) _{16}COO^-] _2Ca^{2+}(s) + 2Na^+(aq)$


Multiple choice chemistry mix and separate different types of solutions various mixtures introduction to solutions

Which of the following is a true solution?

  1. $NaCl$ is sulphur dioxide

  2. Copper in silver

  3. Salt in petrol

  4. Mud in water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

NaCl in sulphur dioxide from molten sodium sulfate. Copper and silver are melted together to forms an alloy, salt is insoluble in petrol because petrol is non-polar solvent. Mud in water forms a colloidal solution, so, from the given options Copper in silver forms a true solution. 

Multiple choice types of cells electricity physics

The depolariser used in Laclanche cell is

  1. Solution of ammonium chloride

  2. Porous pot

  3. Powdered carbon

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

A battery depolarizer takes up electrons during discharge of the cell and thus it is always an oxidizing agent. The term depolarizer has been used to denote a substance used in primary cell to prevent build up of hydrogen gas bubbles. Manganese dioxide is used as depolarizer in Leclanche cell and dry cell.

Multiple choice geography rivers, coasts and glaciation rivers rivers and their work exogenic forces

Carbonation, solution and oxidation are the process of ________.

  1. mechanical weathering

  2. biological weathering

  3. chemical weathering

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Decomposition and disintegration and decomposition of rocks due to chemical reaction is called chemical weathering. Chemical weathering takes place through the process of solution, oxidation and carbonation. Solution refers to the dissolution of soluble particles and minerals from the rocks with the help of water in motion. The atmospheric oxygen in rain water when meet with mineral like iron, rusting takes place and the colour of the rock changes. The process is called oxidation. When the carbon dioxide present in water reacts with rocks new chemical substances like calcium carbonation and iron carbonate are formed. This process is called carbonation.