Chemistry MCQ Quiz - Objective Question with Answer for Chemistry - Download Free PDF

The correct asnwer is ​Dalton's.

Key Points

•  This is known as Dalton's law of partial pressures.
• According to Dalton's law, the total pressure exerted by a mixture of non-reacting ideal gases is equal to the sum of the partial pressures of each individual gas.
• Dalton's law is based on the assumption that the gases in the mixture behave independently of one another, without any significant interactions or reactions.

Additional Information

• Boyle's Law:
  • Boyle's law states that, at a constant temperature, the volume of a given amount of gas is inversely proportional to its pressure.
  • In other words, as the pressure of a gas increases, its volume decreases, and vice versa, provided the temperature remains constant. Mathematically, Boyle's law can be expressed as:
  • P₁V₁ = P₂V₂
  • where P₁ and V₁ are the initial pressure and volume, and P₂ and V₂ are the final pressure and volume, respectively.
• Charles's Law:
  • Charles's law states that, at a constant pressure, the volume of a given amount of gas is directly proportional to its absolute temperature. This means that as the temperature of a gas increases, its volume also increases, and as the temperature decreases, its volume decreases, as long as the pressure remains constant. Mathematically, Charles's law can be expressed as:
  • V₁/T₁ = V₂/T₂
  • where V₁ and T₁ are the initial volume and temperature (in Kelvin), and V₂ and T₂ are the final volume and temperature, respectively.
• Avogadro's Law:
  • Avogadro's law states that, at a constant temperature and pressure, equal volumes of gases contain an equal number of particles (atoms, molecules, or ions).
  • This law implies that the volume of a gas is directly proportional to the number of moles of gas present. Mathematically, Avogadro's law can be expressed as:
  • V₁/n₁ = V₂/n₂

where V₁ and n₁ are the initial volume and number of moles, and V₂ and n₂ are the final volume and number of moles, respectively.

The correct answer is Kerosene.

Key Points

• Sodium cannot be kept in the open air because it is a very reactive metal.
• If it is kept in the open air, it will react with the moisture present in the air and result in the formation of sodium hydroxide (exothermic reaction)
• For this reason, it is kept in kerosene to prevent contact with oxygen and moisture.

Additional Information

• Sodium (Na), chemical element of the alkali metal group Group 1(a) of the periodic table.
  • Sodium is a very soft silvery-white metal.
  • Sodium is the most common alkali metal and the sixth most abundant element on Earth.
  • Comprising 2.8 percent of Earth’s crust.
  • It occurs abundantly in nature in compounds, especially common salt Sodium chloride (NaCl)
  • It forms the mineral halite and constitutes about 80 percent of the dissolved constituents of seawater.

The correct answer is 0° C = 273 K.

Key Points

• The relation between Celsius and Kelvin temperature is  0° C = 273 K.
  • The number of degrees between absolute zero and the freezing temperature of the water is 273 on either temperature scale.
  • Therefore, the freezing temperature of the water is 273 degrees on the Kelvin temperature scale.
  • While the coldest temperature possible on the Celsius temperature scale is -273 degrees.

Additional Information

• The temperature conversion formula from Celsius to Kelvin is:
  • K = C + 273.15
• The temperature conversion formula from Kelvin to Celcius is:
  • C = K − 273.15
• The temperature conversion formula from Fahrenheit to Celsius is:
  • \(C = {(F − 32) ×{ 5\over{9}}}\)
• The Temperature Conversion Formula from Celsius to Fahrenheit is:
  • ​\(F = {C{9\over{5}}} + 32 \)
• ​The Temperature Conversion Formula from Fahrenheit to Kelvin is:
  • \(K = {(F − 32) × {5\over{9}} + 273.15}\)

• Retinol is the fat-soluble vitamin retinol.
• The chemical name of Vitamin A is Retinol.
• Deficiency of vitamin A causes night blindness.
• Vitamin A can be found in many fruits, vegetables, fish and dairy products 

Thus, we can conclude that the chemical name of 'Vitamin A' is Retinol.

Additional Information

Key Points

• When iron comes in contact with air and moisture, rust forms over it and eats away the metal. 
• Rust is hydrated iron oxide with the chemical formula Fe2O3. nH2O.
• Zinc is coated over iron to protect the latter from rusting.
• The most common way of galvanizing iron is dipping it in the hot molten zinc.
• When Zinc gets coated over the iron it protects iron from coming in contact with air and moisture.

Hence, we can conclude that 'Galvanisation' is a process in which Zinc is deposited as layer on iron.

The correct answer is Sodium carbonate.

Explanation:

• Washing soda is a chemical compound with the formula Na2CO3, known as sodium carbonate, and it's a salt of carbonic acid.
• Properties of a Washing soda:
  • It is a transparent crystalline solid.
  • It is one of the few metal carbonates which are soluble in water.
  • It is alkaline with a pH level of 11, it turns red litmus to blue.
  • It has detergent properties or cleansing properties because it can remove dirt and grease from dirty clothes, etc.
  • It attacks dirt and grease to form water-soluble products, which are then washed away on rinsing with water. 

 Important Points

Some common chemical compounds with their common names are:

K2CO3 or potassium carbonate is known as pearl ash.

• Pearl ash, in ancient times, was created by baking potash in a kiln in order to remove impurities. The remaining fine, white powder was pearl ash.
• Potassium carbonate is an inorganic compound and a white salt which is soluble in water.
• It is mainly used in the production of glass and soap.

Additional Information

The correct answer is Lactic Acid.

Key Points

• Lactic acid is present in Sour milk or curd.
• The sourness of the milk is due to the presence of lactic acid.
• Human beings feel tired due to the accumulation of lactic acid in the muscles.​

Additional Information

 Key Points

• Atomic Mass of the Hydrogen = 1
• Atomic Mass of the oxygen = 16

Explanation:

1 mole of hydrogen = 1gm

1 mole of oxygen = 16gm

Water (H2O) = 2 Hydrogen atoms + 1 Oxygen atom

2 mole of hydrogen = 2gm

1 mole of oxygen = 16 gm

The ratio of the mass of Hydrogen: Ratio of mass of Oxygen =  2/16 = 1/8 

The ratio of the mass of Hydrogen to the mass of Oxygen in water is always 1:8.

• The number of water molecules present is washing soda is 10.
• We know the molecular formula for Washing Soda is Na₂CO₃.10H₂O.
• Recrystallisation of Sodium Carbonate (Na₂CO₃) gives washing soda.
• In a Washing soda, water is present in the form of crystals.

The correct answer is Vermilion.

• Mercury Sulfide is also known as Vermilion.
• It is a chemical compound composed of the chemical elements mercury and sulfur.
• The chemical formula of Mercury sulfide is HgS.
• It is dimorphic with two crystal forms:
  • Red cinnabar
  • Black metacinnabar

Additional Information

• Marsh Gas is the common name of Methane with the formula of CH₄.
• Mohr's Salt is the common name of Ammonium Ferrous Sulphate with the formula of (NH₄)2Fe(SO₄)₂(H₂O)₆.
• Potash Alum is the common name of Potassium Aluminium Sulphate with the formula of KAl(SO₄)₂.

Explanation:

• Calcium hydroxide is sparingly soluble in water producing an alkaline solution known as limewater.
• Calcium Carbonate is a chemical compound found commonly in rocks as minerals and is the main component of pearls and the shells of marine organisms, eggs, etc.
• When carbon dioxide gas is passed through or over limewater, it turns milky due to the formation of calcium carbonate.
• In the chemical reaction it can be shown as :

\(\rm \underset{Lime\ water}{Ca (OH)_2} \ (aq) \ + \ \underset{Carbon \ Dioxide}{CO_2 \ (g) }\ \longrightarrow \ \underset{Calcium \ Carbonate}{CaCO_3 \ (g)}\)Ca(OH)2Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate" id="MathJax-Element-1-Frame" role="presentation" style="display: inline; position: relative;" tabindex="0">Ca(OH)2Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate" role="presentation" style="display: inline; position: relative;" tabindex="0">Ca(OH)2

• However, when an excess of CO2 ​is passed through this solution, the milkiness disappears. This is due to the formation of calcium bicarbonate which is colorless and soluble in water.

Ca(OH)2Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate" role="presentation" style="display: inline; position: relative;" tabindex="0">​\(\rm \underset{Lime\ water}{Ca (OH)_2} \ (aq) \ + \ \underset{Carbon \ Dioxide}{CO_2 \ (g) }\ \longrightarrow \ \underset{Calcium \ Carbonate}{CaCO_3 \ (g)}\)​\(\rm \underset{Lime\ water}{Ca CO_3} \ (aq) \ + \ \underset{Carbon \ Dioxide}{CO_2 \ (g) }\ \longrightarrow \ \underset{Calcium \ Carbonate}{Ca(HCO_3)_2 \ (g)}\)Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate\(\rm \underset{Calcium\ Carbonate}{Ca CO_3} \ \ +H_2O+ \ \underset{Carbon \ Dioxide}{CO_2 \ (g) } \ \longrightarrow \ \underset{Calcium \ bi\ Carbonate}{Ca(HCO_3)_2 \ (g)}\)

Additional Information Reaction involved-

CaCO₃ + 2HCl →  CaCl₂ + CO₂ + H₂O

• The evolved gas is carbon dioxide which then passes through lime water and turns it milky.

Ca(OH)₂ + CO₂ → H₂O + CaCO₃  

• Due to formation of these compounds
• when excess CO₂ is passed

CaCO₃ + H₂O + CO₂ →  Ca(HCO₃)₂ 

• Bicarbonate is formed which again clears the solution

Mistake Points

•  Do not confuse Calcium carbonate and calcium bicarbonate.
• One produces white colour while the other makes it colourless.

The correct answer is Double displacement reaction.

Concept:

Chemical reaction:

• It is a process in which one or more substances, the reactants, are converted to one or more different substances, the products.
• A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Explanation:

• Double displacement reaction: 

• It is a chemical reaction in which two compounds react and exchange their ions forming new products. 
• This reaction often results in the formation of an insoluble compound called a precipitate. 
• Such reactions are represented by equations of the following form: A⁺B^- + C⁺D^- → A⁺D^- + B^-C⁺

​In the given chemical reaction: 

NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)

The reactants NaCl and AgNO₃ have exchanged their ions to form NaNO3  and AgCl. 

Thus, it is an example of a double displacement reaction.^​

^{Additional Information}

Types of Chemical Reactions:

Combination reaction:

• Two or more elements or compounds combine together to form a single compound.
• Such reactions are represented by equations of the following form:     A + B → AB.

Decomposition reaction:

• The opposite of a combination reaction, a complex molecule breaks down to make simpler ones.
• Such reactions are represented by equations of the following form: AB → A + B.

Displacement reaction:

• One element takes place with another element in the compound.
• Such reactions are represented by equations of the following form: A + BC → AC + B.

Redox reaction:

• It is a reaction in which one species is reduced and the other is oxidized. 
• Reduction means losing Oxygen or gaining hydrogen 
• Oxidation means gaining oxygen or losing hydrogen. 

pH of some common aqueous solutions

• Aluminium (Al) metal reacts with steam to form a metal oxide and hydrogen.
• This reaction can be given as

2Al + 3H₂O (g) → Al₂O₃ + 3H₂ (g)

• Other metals of this type are Iron (Fe) and Zinc (Zn).

• But these metals do not react with either hot or cold water.