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

The correct answer is option 3, i.e. Solid solution.

Alloy is an example of a solid solution.

• Alloy is the fusion or mixing of two or more metals and metals with non-metals.
  • Example of an alloy is Brass that is a mixture of copper and zinc.
  • The property of the resulting mixture differs from pure metals. For example, increasing hardness.
  • An alloy retains all the property of metal-like electrical conductivity, ductility, lustre etc.
  • Alloys are used in applications like building, automobiles, surgical tools and aerospace industry etc.
• A colloidal solution is a mixture in which substances are regularly suspended in the fluid. For example, plaster, paper, milk, gelatine, jelly etc.
• The emulsion is a mixture of two or more liquids which are not soluble. For example egg yolk, butter.
• A heterogeneous mixture is a mixture of non-uniform composition. The mixture of two or more phases is called a heterogeneous mixture. For example, ice cubes in a drink, oil and water, salt and oil etc.

The correct answer is molality.

Concept:

• Molarity:
  • It is defined as the moles of a solute per litres of a solution.
  • It is also known as the molar concentration of a solution.
• Molality:
  • It is defined as the number of moles of solute per kilogram of solvent.
• Mole fraction:
  • It is the ratio of moles of a component with the total moles of solute and solvent.
• Mass%:
  • It is the percentage of the mass of solute or solvent w.r.t total mass of solution.
• Formulas:​

Explanation:

• Molality depends on the mass of the solvent.
• And ,mass is not dependent on temperature.
• So, Molality is independent of temperature.

​Additional Information

Notes:

• Normality:
  • It is defined as the number of gram equivalent per litre of solution.
  • Also known as equivalent concentration.
  • Normality = Number of gram equivalents / [volume of solution in litres]
• Normality is inversely proportional to temperature.
• ​Volume is directly proportional to temperature.
• Molarity is inversely proportional to volume.
• Molarity is inversely proportional to temperature.
• Molality is not dependent on temperature.

Mistake Points

• Molarity depends on the volume of the solution.
• And volume is directly proportional to temperature.
• And when we increase the temperature the volume will increase.
• So the increase in volume leads to a decrease in Molarity as Molarity is inversely proportional to the volume of solution

The correct answer is Starch solution.

Key Points

• Tyndall effect also called the Tyndall phenomenon is the scattering of a beam of light by a medium containing small suspended particles—e.g., smoke or dust in a room, which makes visible a light beam entering a window.
• This effect is exhibited by all colloidal solutions and some very fine suspensions.
• The intensity of scattered light depends on the density of the colloidal particles as well as the frequency of the incident light.
• The effect is named for the 19th-century British physicist John Tyndall, who first studied it extensively.
• Milk and Starch solution will show the Tyndall effect because of the presence of suspended particles.
• Sugar solution, Salt solution and Copper sulphate solution are examples of true solutions.
• They will not show the Tyndall effect because of the absence of suspended particles.

Additional Information

• A true solution is a homogeneous mixture with consistent properties.
• Filtration cannot separate the solute from the solution in a true solution.

The correct answer is "Physical Change".

Key Points 

• Physical change is a type of change where the physical properties of matter change. A change of state of matter, change in color, odor, solubility, etc. all are examples of physical change.
• During a physical change, neither the composition nor the chemical nature of matter is changed. During this change, molecules rearrange themselves without affecting the internal composition. A physical change doesn't affect the chemical property.
• Dissolution of sugar in water is a physical change because it doesn't result in the formation of a new substance. It is a reversible change as sugar and water can be extracted back from the solution by the process of crystallization followed by evaporation.

 Additional Information

• Chemical Change is a change of material into another. New materials with different properties and one or more than one new substance are formed.

Explanation:

• When non-metals are dissolved in water they produce acidic oxides.
• And most metals, give rise to basic oxides.
• The formation of H⁺ (aq) ions in solution causes a substance's acidic nature.
• The formation of OH^– (aq) ions in solution are responsible for a substance's basic nature.
• Non-metals do not react with water but the non-metal oxides do react with water and they produce acids.
• Non-metallic oxide dissolves in water to form an acid.
  • CO₂ + H₂O → H₂CO₃
• Carbonic acid (H₂CO₃) is an acid formed by the reaction of water (H₂O) with carbon oxide (CO₂).

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 increases.

Important Points

• In normal cases, the volume of substances increases on heating and decreases while cooling.
• When 1 litre of water is cooled from 4°C to 0°C volume of water will start increasing this due to water's unique property known as 'Anomalous Expansion of Water'.
• Anomalous Expansion of Water occurs between 4°C to 0°C.
• The density of water is a maximum at 4 °C.
• When water is cooled from 4°C to 0°C, its density decreases.
• The anomalous expansion of water helps preserve aquatic life during very cold weather.

Explanation:

• When water reaches 4°C the molecules have been pushed as close to one another as possible and the density of water becomes precisely 1.00 g/cm³
• When water freezes at 0°C due to the crystal structure the molecules arranged in some structured fashion so a little far apart ended up less dense - 0.93 g/cm³  - and so floats due to buoyancy.

As density decreases the volume increases.

Volume = mass /density.

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 :

">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">​​Lime water (aq) + CO2 (g)Carbon Dioxide ⟶ CaCO3 (g)Calcium Carbonate

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 Methanoic acid.

Key Points

• Nettle is an herbaceous plant that grows in the wild.
• Nettle leaves have stinging hair, which causes painful stings when touched accidentally. 
• This is due to the methanoic acid secreted by them. 
• A traditional remedy is rubbing the area with the leaf of the dock plant, which often grows beside the nettle.

Additional Information

The correct answer is option 1, i.e  Alkali Metals.

EXPLANATION:

• The elements in the first group of s-block are also known as Alkali Metals. These have only one electron in their outermost shell and hence are quite reactive as they easily lose their electron to form bonds with non-metals.

• The elements in the second group of s-block are also known as Alkaline Earth Metals. These have two electrons in their outermost shell and are less reactive than Alkali metals.
• Halogens are the group 17 elements and are placed in the p-block.
• Noble gases are the group 18 elements and are placed in the p-block. These are the least reactive amongst all the elements found in the periodic table as they have a stable configuration.

The correct answer is The acid present in tomatoes.

Key Points

• Oxalic acid is a chemical compound that occurs naturally in almost every plant to some degree, including fruit, vegetable and grain plants. 
• Tomato contains more than 10 types of acids such as citric acid, malic acid, ascorbic acid, oxalic acid etc. 
• The oxalic acid content of tomatoes is about 50 mg per 100 g serving. 

Additional Information 

• Some natural sources of acid:

• The word ‘atom’ is coined by Democritus.
• He suggested that if we go on dividing matter at a certain point the atom becomes indivisible or cannot be divided further.
• He called these particles as atoms (Indivisible).

 

Scientist	Discovered
Thomson	Electron
E Rutherford	Discovered alpha and beta particles
John Dalton	Father of Atomic Theory

• 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 green.

Key Points 

• Barium Nitrate Ba(NO₃)₂ is an Oxidizer used to produce green colour in fireworks and fountains.
• This compound is also used in the production process of Barium Oxide in the vacuum tube industry.
• Barium is also used in medicine and oil and gas production.
• It is an inorganic compound that occurs with other elements like sulfur, oxygen, etc.
• Barium is found at 0.0425% on the earth’s crust, and 13 μg/L in seawater.
• It is a non-combustible compound but enhances the burning of combustible elements.
• The melting point of barium nitrate is 592 degrees Celcius.​

Additional Information