Mastering Parajumbles: Tips, Tricks, and Examples for Competitive Exams

Are you preparing for RRB exams like RRB ALP, RRB Technician, or RRB NTPC? Chemistry is a pivotal subject that can greatly impact your exam performance.

To help your preparation for the Chemistry section, we've curated the Top 100 Most Important (and most repeated) Chemistry Questions frequently asked in various RRB exams. This comprehensive guide not only provides essential questions but also offers valuable insights into key topics and effective study strategies.

Most Asked Chemistry Topics for RRB Exams

Focusing on the right topics can optimize your preparation and enhance your efficiency. Below is a table highlighting the Most Asked Chemistry Topics in RRB exams, along with the number of questions (in the top 100 questions) typically associated with each topic.

Chemistry Topic	Number of Questions	Key Areas Covered
Periodic Table	24	History, structure, properties, trends, groups, and periods
Chemical Reactions	15	Types of reactions, neutralization, double displacement, redox reactions
Atomic Structure	12	Electrons, protons, neutrons, isotopes, atomic number, mass number
Chemical Bonding	8	Valency, electronic configuration, molecular formulas
Acids, Bases, and Salts	7	Properties, reactions, neutralization, pH
Metals and Non-metals	7	Properties, uses, reactions with acids
Organic Chemistry	6	Hydrocarbons, functional groups, esters, acetic acid
States of Matter	5	Solids, liquids, gases, phase changes, sublimation, evaporation
Solutions and Mixtures	4	Types of mixtures, solutions, suspensions, colloids
Industrial Chemistry	4	Manufacturing processes, uses of chemicals in industry
Environmental Chemistry	3	Biogas, pollution, greenhouse gases
Nuclear Chemistry	2	Radioactivity, isotopes, nuclear reactions
Electrochemistry	2	Electrolysis, batteries, corrosion
Analytical Chemistry	2	Titration, indicators, qualitative analysis
Inorganic Chemistry	2	Compounds, oxides, halogens, noble gases
Thermochemistry	1	Heat, energy changes in reactions
Coordination Compounds	1	Structure, nomenclature, properties

Note: Prepare effectively for RRB exams with this MCQs set of most repeated GK questions from previous RRB exams.

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Top 100 Important Chemistry GKQuestions for RRB Exam

Practice Show All Answers

Q1: Which of the following metals is a liquid at room temperature?

A. Copper

B. Iron

C. Mercury

D. Aluminium

Mercury is the only metal that is liquid at room temperature. This is due to its unique electronic configuration, which makes it difficult for the atoms to bond strongly to each other.

Q2: The process in which acids and bases react to form salts and water is called ______ reaction.

A. Displacement

B. Combustion

C. Decomposition

D. Neutralisation

Neutralisation is the reaction between an acid and a base, which results in the formation of a salt and water. This is a fundamental concept in chemistry, with applications in various industries and daily life. The general reaction can be written as: \[ \text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water} \] For example: \[ \text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O} \]

Q3: Name the German chemist who grouped elements into triads in 1817.

A. John Newlands

B. Henry Moseley

C. Johann Wolfgang Dobereiner

D. Dmitri Mendeleev

Johann Wolfgang Dobereiner is known for grouping elements into triads, which were groups of three elements with similar properties. This was one of the early attempts to organize elements based on their properties.

Q4: What are the chemical formulas of gypsum and plaster of Paris, respectively?

A. \(\text{CaCO}_3\) and \(\text{CaSO}_4 \cdot \frac{1}{2}\text{H}_2\text{O}\)

B. \(\text{CaSO}_4\) and \(\text{CaCO}_3 \cdot \frac{1}{2}\text{H}_2\text{O}\)

C. \(\text{CaSO}_4 \cdot 2\text{H}_2\text{O}\) and \(\text{CaSO}_4 \cdot \frac{1}{2}\text{H}_2\text{O}\)

D. \(\text{CaSO}_4 \cdot \frac{1}{2}\text{H}_2\text{O}\) and \(\text{CaSO}_4 \cdot 2\text{H}_2\text{O}\)

Gypsum is calcium sulfate dihydrate (\(\text{CaSO}_4 \cdot 2\text{H}_2\text{O}\)), and plaster of Paris is calcium sulfate hemihydrate (\(\text{CaSO}_4 \cdot \frac{1}{2}\text{H}_2\text{O}\)). Plaster of Paris is obtained by heating gypsum to drive off part of the chemically combined water.

Q5: In the process of ______, the iron is protected by a coating of zinc.

A. electroplating

B. passivation

C. galvanisation

D. anodization

Galvanisation is the process of applying a protective zinc coating to steel or iron to prevent rusting. This is widely used in industries to protect metals from corrosion.

Q6: According to Newlands’ Law of Octaves, how many elements exist in nature?

A. 118

B. 92

C. 63

D. 56

Newlands' Law of Octaves stated that when elements are arranged in order of increasing atomic weights, the eighth element is a kind of repetition of the first, like the eighth note in an octave of music. He identified 56 elements known at that time.

Q7: In Mendeleev’s periodic table, the properties of the elements are considered a periodic function of them.

A. Atomic number

B. Atomic mass

C. Ionization energy

D. Electronegativity

Mendeleev arranged the elements based on their atomic masses and observed that the properties of elements recur periodically. This led to the development of the periodic table.

Q8: Consider the below statements and identify the correct answer. Statement-I: The chemical formula for baking soda is \(\text{NaHCO}_3\). Statement-II: It is used in soda-acid fire extinguisher.

A. Both the statements are true

B. Both the statements are false

C. Statement-I is true, Statement-II is false

D. Statement-I is false, Statement-II is true

Baking soda (\(\text{NaHCO}_3\)) is indeed used in soda-acid fire extinguishers. When it reacts with acid, it produces carbon dioxide, which helps to extinguish the fire.

Q9: What is the common name of the compound \(\text{CaOCl}_2\)?

A. Bleaching powder

B. Quick lime

C. Slaked lime

D. Lime water

Bleaching powder is calcium oxychloride (\(\text{CaOCl}_2\)). It is commonly used as a disinfectant and bleaching agent due to its strong oxidizing properties.

Q10: The process whereby a liquid (water) changes into a gas (water vapour) is called ______.

A. Condensation

B. Evaporation

C. Freezing

D. Sublimation

Evaporation is the process by which a liquid changes into a gas or vapor. This process is essential in the water cycle and various industrial applications.

Q11: The maximum number of electrons that can be accommodated in a shell depends on the formula:

A. \(2n^2\)

B. \(2n+2\)

C. \(n^2\)

D. \(2n\)

The maximum number of electrons in a shell is given by \(2n^2\), where \(n\) is the shell number. This formula helps in understanding the electronic configuration of atoms.

Q12: Which is called nucleon?

A. Electrons and Neutrons

B. Electrons and Protons

C. Protons and Neutrons

D. Protons and Electrons

Nucleons are the particles present in the nucleus of an atom, which include protons and neutrons. They are responsible for the mass and stability of the nucleus.

Q13: How many atoms are present in one molecule of Ozone?

A. 4

B. 5

C. 2

D. 3

Ozone (\(\text{O}_3\)) is a molecule composed of three oxygen atoms. It is a powerful oxidizing agent and plays a crucial role in the Earth's atmosphere.

Q14: Up to which element was the law of octaves found to be applicable?

A. Magnesium

B. Sodium

C. Calcium

D. Potassium

Newlands' Law of Octaves was found to be applicable up to calcium, which was the 56th element known at that time.

Q15: Name the chemist who proved that the atomic number of an element is more fundamental property than its atomic mass, which led to modification in the Mendeleev’s Periodic Law table?

A. Henry Moseley

B. Dmitri Mendeleev

C. Johann Wolfgang Dobereiner

D. John Newlands

Henry Moseley's work on X-ray spectra showed that the atomic number (number of protons) is a more fundamental property than atomic mass. This led to the modern periodic table arrangement.

Q16: How many groups and periods are present in the Modern Periodic Table?

A. 17 groups, 8 periods

B. 18 groups, 8 periods

C. 17 groups, 7 periods

D. 18 groups, 7 periods

The Modern Periodic Table consists of 18 groups (columns) and 7 periods (rows). This arrangement helps in predicting the properties of elements based on their position.

Q17: From total ______ elements, ______ elements were discovered through laboratory processes.

A. 116, 24

B. 118, 20

C. 118, 24

D. 116, 20

There are 118 known chemical elements, out of which 24 are synthetic, meaning they were created in laboratories through nuclear reactions.

Q18: Which one of the following elements is polyatomic?

A. Oxygen

B. Sulphur

C. Hydrogen

D. Nitrogen

Sulphur is polyatomic, meaning its molecules consist of more than two atoms. In its most common form, sulphur exists as \(\text{S}_8\) molecules.

Q19: The electronic configuration of an element is 2, 8, 8. It belongs to group ____.

A. 15

B. 16

C. 18

D. 17

The electronic configuration 2, 8, 8 corresponds to the noble gas Argon (Ar), which belongs to group 18 of the periodic table.

Q20: Which of the following reactions is an example of double displacement?

A. \(2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}\)

B. \(\text{Na}_2\text{SO}_4 (aq) + \text{BaCl}_2 (aq) \rightarrow \text{BaSO}_4 (s) + 2\text{NaCl} (aq)\)

C. \(\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2\)

D. \(\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}\)

In a double displacement reaction, the ions of two compounds exchange partners to form two new compounds. The given reaction is an example of this type.

Q21: The insoluble substance formed in a solution during a chemical reaction is known as ______.

A. precipitate

B. solute

C. colloid

D. solvent

A precipitate is an insoluble solid that forms in a solution during a chemical reaction. This is often observed in reactions involving ionic compounds.

Q22: Blue litmus when added to an acidic solution changes to ______.

A. Green

B. Blue

C. Red

D. Yellow

Litmus is a natural dye that changes color in response to acids and bases. Blue litmus turns red in acidic solutions, indicating the presence of hydrogen ions (\(\text{H}^+\)).

Q23: What is the property of metal by which it can be brought in the form of wire?

A. Ductility

B. Lustre

C. Conductivity

D. Malleability

Ductility is the property of a metal that allows it to be drawn into thin wires without breaking. This property is crucial in various industrial applications.

Q24: Sublimation is the ______.

A. transition of a substance directly from the gas to the liquid state

B. transition of a substance directly from the solid to the gas state

C. transition of a substance directly from the liquid to the gas state

D. transition of a substance directly from the gas to the solid state

Sublimation is the process where a solid changes directly into a gas without passing through the liquid state. Examples include dry ice (solid \(\text{CO}_2\)) and iodine.

Q25: A homogeneous mixture of two or more substances is known as the ______.

A. Solution

B. Colloid

C. Emulsion

D. Suspension

A solution is a homogeneous mixture of two or more substances. The particles of the solute are evenly distributed throughout the solvent, forming a single phase.

Q26: Name the technique used to separate butter from curd.

A. Centrifugation

B. Filtration

C. Distillation

D. Decantation

Centrifugation is a technique used to separate components of a mixture based on their densities. It is commonly used to separate butter from curd in the dairy industry.

Q27: Name the scientist who proposed that electrons are embedded in a positive sphere.

A. Niels Bohr

B. Ernest Rutherford

C. Robert Millikan

D. J.J. Thomson

J.J. Thomson proposed the "plum pudding" model of the atom, where electrons are embedded in a positively charged sphere. This was an early attempt to explain the structure of the atom.

Q28: The electrons present in the ______ of an atom are known as the valence electrons.

A. Outermost shell

B. Nucleus

C. Innermost shell

D. Penultimate shell

Valence electrons are the electrons present in the outermost shell of an atom. They are involved in chemical bonding and determine the chemical properties of the element.

Q29: What is defined as the total number of protons present in the nucleus of an atom?

A. Atomic number

B. Neutron number

C. Mass number

D. Atomic mass

The atomic number (\(Z\)) is the number of protons in the nucleus of an atom. It determines the element's identity and its position in the periodic table.

Q30: The term ‘Isotope’ refers to:

A. elements having the same number of electrons

B. elements having the same mass number but different atomic numbers

C. elements having the same number of neutrons

D. elements having the same atomic number but different mass number

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. They have the same atomic number but different mass numbers.

Q31: ______ are atoms having the same mass number but different atomic numbers

A. Isotopes

B. Isoelectronic

C. Isobars

D. Isotones

Isobars are nuclides having the same mass number but different atomic numbers. They have the same number of nucleons but different numbers of protons and neutrons.

Q32: In Newland’s octave, which of the following pairs of elements were placed in the same column along with H, F, Cl and Br?

A. Co and Ni

B. Fe and Mn

C. Zn and Cd

D. Cu and Ag

In Newlands' octave, cobalt (Co) and nickel (Ni) were placed in the same column along with hydrogen (H), fluorine (F), chlorine (Cl), and bromine (Br). This was based on their similar properties.

Q33: Who stated the law: ‘The properties of the elements are the periodic function of their atomic masses’?

A. Newlands

B. Bohr

C. Mendeleev

D. Moseley

Dmitri Mendeleev stated the periodic law, which says that the properties of elements are a periodic function of their atomic masses. This led to the development of the periodic table.

Q34: The name of group 17 elements is:

A. Halogens

B. Alkaline earth metals

C. Alkali metals

D. Transition metals

Group 17 elements are known as halogens. They are highly reactive non-metals and include elements like fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

Q35: The most electronegative element in the periodic table is:

A. bromine

B. oxygen

C. fluorine

D. chlorine

Fluorine is the most electronegative element in the periodic table. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.

Q36: Which of the following properties remain the same while moving down the group in the periodic table?

A. Ionization energy

B. Atomic radius

C. Valency

D. Electronegativity

Valency tends to remain the same within a group because elements in the same group have the same number of valence electrons. Other properties like atomic radius, ionization energy, and electronegativity change.

Q37: The reaction in which two compounds exchange their ions to form two new compounds is called:

A. Decomposition reaction

B. Single displacement reaction

C. Double displacement reaction

D. Combustion reaction

In a double displacement reaction, the positive ions (cations) and negative ions (anions) of two compounds exchange partners to form two new compounds. This is also known as a metathesis reaction.

Q38: If a substance gains hydrogen during a reaction, it is said to be:

A. hydrolyzed

B. neutralized

C. reduced

D. oxidized

Reduction is the gain of hydrogen or electrons during a chemical reaction. This process is often accompanied by the loss of oxygen or other electronegative elements.

Q39: Which gas is typically produced when metal reacts with acids?

A. Hydrogen

B. Oxygen

C. Carbon dioxide

D. Nitrogen

When a metal reacts with an acid, hydrogen gas (\(\text{H}_2\)) is typically produced. This is a common reaction observed in the laboratory and industrial settings. The general reaction can be written as: \[ \text{Metal} + \text{Acid} \rightarrow \text{Salt} + \text{H}_2 \] For example: \[ \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \]

Q40: Which product is formed due to the burning of a magnesium ribbon with a spirit lamp?

A. Magnesium chloride

B. Magnesium sulfate

C. Magnesium oxide

D. Magnesium hydroxide

When a magnesium ribbon is burned in air, it reacts with oxygen to form magnesium oxide (\(\text{MgO}\)). This reaction is highly exothermic and produces a bright white light. The reaction can be written as: \[ 2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO} \]

Q41: Which of the following acids is present in Red Ants?

A. Lactic acid

B. Formic acid

C. Acetic acid

D. Citric acid

Formic acid (\(\text{HCOOH}\)) is present in red ants and is responsible for the painful sting. It is also found in other insects and plants.

Q42: If any person is affected by a bee-sting attract, which chemical would be helpful for him to get some relief from pain?

A. Vinegar

B. Hydrogen peroxide

C. Baking soda

D. Ammonia

Baking soda (\(\text{NaHCO}_3\)) can help neutralize the acidic components of a bee sting, providing relief from pain and itching. It is a common household remedy for insect stings.

Q43: Washing soda is:

A. a neutral salt

B. a basic salt

C. an acidic salt

D. an amphoteric salt

Washing soda is sodium carbonate (\(\text{Na}_2\text{CO}_3\)), which is a basic salt. It is commonly used in cleaning and laundry due to its alkaline properties.

Q44: Which is used in the manufacturing of sodium components like borax?

A. Washing soda

B. Caustic soda

C. Baking soda

D. Soda ash

Washing soda (\(\text{Na}_2\text{CO}_3\)) is used in the manufacturing of sodium components like borax. It is an important industrial chemical with various applications.

Q45: At what temperature does gypsum get converted into Plaster of Paris?

A. 373 K

B. 363 K

C. 393 K

D. 353 K

Gypsum (\(\text{CaSO}_4 \cdot 2\text{H}_2\text{O}\)) is heated to about 373 K (100°C) to drive off part of the chemically combined water, forming plaster of Paris (\(\text{CaSO}_4 \cdot \frac{1}{2}\text{H}_2\text{O}\)). This process is essential in the construction industry.

Q46: A chemical compound X is prepared by heating gypsum. It is white powder and used as a fireproofing material.

A. chalk

B. cement

C. lime

D. plaster of Paris

Plaster of Paris is prepared by heating gypsum. It is a white powder used in construction for making surfaces fireproof and for creating molds and casts.

Q47: Which gas is utilised during the preparation of bleaching powder?

A. Nitrogen

B. Carbon dioxide

C. Chlorine

D. Oxygen

Chlorine gas (\(\text{Cl}_2\)) is used in the preparation of bleaching powder (calcium oxychloride, \(\text{CaOCl}_2\)). The reaction involves passing chlorine gas over dry slaked lime (calcium hydroxide, \(\text{Ca(OH)}_2\)).

Q48: Litmus is a natural acid-base indicator that is extracted from:

A. Lichen

B. Fungi

C. Bacteria

D. Algae

Litmus is a natural dye extracted from lichens. It is used as an acid-base indicator, turning red in acidic solutions and blue in basic solutions.

Q49: Our body works within the pH range of:

A. 5.5 to 6.5

B. 7 to 7.8

C. 6 to 7

D. 7.8 to 8.5

The human body maintains a pH range of 7 to 7.8, which is slightly alkaline. This pH range is crucial for the proper functioning of enzymes and biological processes.

Q50: What is the process called when a substance’s spontaneous movement from a high concentration to a low concentration takes place?

A. Active transport

B. Filtration

C. Diffusion

D. Osmosis

Diffusion is the spontaneous movement of particles from an area of high concentration to an area of low concentration. This process is driven by the random motion of particles and is essential in various biological and chemical systems.

Q51: Biogas is an excellent fuel as it contains ______ up to 75%.

A. Carbon dioxide

B. Oxygen

C. Hydrogen

D. Methane

Biogas is a renewable fuel produced from the anaerobic digestion of organic matter. It contains up to 75% methane (\(\text{CH}_4\)), making it an excellent fuel for various applications.

Q52: Which of the following allotropes of carbon is the hardest natural substance known that has a very high melting and boiling point?

A. Diamond

B. Graphene

C. Fullerene

D. Graphite

Diamond is the hardest natural substance known, with a very high melting and boiling point. It is an allotrope of carbon with a unique crystal structure that gives it exceptional properties.

Q53: Which type of coal has the highest percentage of carbon?

A. Bituminous

B. Anthracite

C. Peat

D. Lignite

Anthracite coal has the highest percentage of carbon, typically around 92-98%. It is the most metamorphosed type of coal, with a high energy content and low moisture.

Q54: The molecular formula of Propane is:

A. \(\text{C}_4\text{H}_{10}\)

B. \(\text{C}_3\text{H}_8\)

C. \(\text{CH}_4\)

D. \(\text{C}_2\text{H}_6\)

Propane (\(\text{C}_3\text{H}_8\)) is a hydrocarbon with the molecular formula \(\text{C}_3\text{H}_8\). It is a colorless, odorless gas commonly used as a fuel in various applications.

Q55: Which of the following is an ore of aluminium?

A. Bauxite

B. Galena

C. Magnetite

D. Hematite

Bauxite is the primary ore of aluminium. It is a sedimentary rock with a relatively high aluminium content, making it the world's main source of aluminium.

Q56: Solder is an alloy of ______.

A. Copper and zinc

B. Lead and tin

C. Iron and carbon

D. Aluminium and magnesium

Solder is an alloy of lead and tin, commonly used in electronics and plumbing to join metallic parts. It has a low melting point, making it suitable for soldering applications.

Q57: Non-metal oxides are usually:

A. basic

B. acidic

C. amphoteric

D. neutral

Non-metal oxides are usually acidic. They react with water to form acids or with bases to form salts and water. Examples include carbon dioxide (\(\text{CO}_2\)) and sulfur dioxide (\(\text{SO}_2\)).

Q58: Which substances are used in making perfumes and aromatic substances?

A. Ester

B. Alcohol

C. Aldehyde

D. Ether

Esters are organic compounds that are often used in making perfumes and aromatic substances due to their pleasant odors. They are formed by the reaction of an alcohol with a carboxylic acid.

Q59: Which type of medicine is used to treat indigestion?

A. Antacid

B. Antihistamine

C. Antipyretic

D. Antibiotic

Antacids are used to treat indigestion by neutralizing stomach acid. They provide relief from symptoms such as heartburn and acid reflux.

Q60: Which of the following compounds is/are used in black and white photography?

A. Silver chloride and silver bromide both

B. Silver nitrate

C. Silver oxide

D. Silver sulfate

Silver chloride (\(\text{AgCl}\)) and silver bromide (\(\text{AgBr}\)) are used in black and white photography. They are light-sensitive compounds that form the basis of photographic film and paper.

Q61: What is the name of the IUPAC of acetic acid?

A. Methanoic acid

B. Ethanoic acid

C. Butanoic acid

D. Propanoic acid

The IUPAC name for acetic acid is ethanoic acid. It is a simple carboxylic acid with the formula \(\text{CH}_3\text{COOH}\), commonly found in vinegar.

Q62: Which chemical is known as dry ice?

A. Solid Oxygen

B. Solid Hydrogen

C. Solid Carbon Dioxide

D. Solid Nitrogen

Dry ice is the solid form of carbon dioxide (\(\text{CO}_2\)). It is used for cooling and freezing due to its low temperature of -78.5°C and its ability to sublime directly into a gas.

Q63: What do we call a positively charged ion?

A. A molecule

B. A radical

C. An anion

D. A cation

A cation is a positively charged ion, formed when an atom or molecule loses one or more electrons. Cations are attracted to the cathode (negative electrode) in an electrolytic cell.

Q64: The basic form of matter which cannot be broken into simpler substances by chemical reactions is called:

A. Mixtures

B. Compounds

C. Elements

D. Solutions

Elements are the basic forms of matter that cannot be broken down into simpler substances by chemical reactions. They are the building blocks of all matter.

Q65: Which of the following is a chemical change?

A. Butter turning rancid

B. Sugar dissolving in water

C. Ice melting

D. Paper being torn

Butter turning rancid is a chemical change because it involves a change in the chemical composition of the butter, forming new substances with different properties.

Q66: Intermolecular forces of attraction are least effective in ______.

A. Liquids

B. Solids

C. Gases

D. Plasmas

Intermolecular forces of attraction are least effective in gases due to the large distances between molecules. This results in the low density and high compressibility of gases.

Q67: Name the British chemist who presented his atomic theory in 1808, on conservation of mass and law of definite proportions, which was a turning point in the study of matter.

A. Amedeo Avogadro

B. Antoine Lavoisier

C. Robert Boyle

D. John Dalton

John Dalton presented his atomic theory in 1808, which included the concepts of the conservation of mass and the law of definite proportions. This theory laid the foundation for modern atomic theory.

Q68: The sum of the number of neutrons and protons present in the nucleus is called ______ of the atom.

A. mass number

B. atomic number

C. neutron number

D. electron number

The mass number (\(A\)) is the sum of the number of protons (\(Z\)) and neutrons (\(N\)) in the nucleus of an atom. It is approximately equal to the atomic mass of the atom.

Q69: The atomic number of an element is the number of ______ in the nucleus of each atom of that element.

A. protons

B. electrons

C. neutrons

D. nucleons

The atomic number (\(Z\)) is the number of protons in the nucleus of an atom. It determines the element's identity and its position in the periodic table.

Q70: The number of neutrons in an atom is equal to the:

A. Mass number + atomic number

B. Atomic number + neutron number

C. Atomic number - mass number

D. Mass number - atomic number

The number of neutrons (\(N\)) in an atom is equal to the mass number (\(A\)) minus the atomic number (\(Z\)). This relationship is expressed as \(N = A - Z\).

Q71: Atoms of the same element or of different elements can join together to form ______.

A. Ions

B. Compounds

C. Molecules

D. Mixtures

Molecules are formed when atoms of the same element or different elements join together. They are the smallest particles of a substance that retain the chemical properties of the substance.

Q72: How many atoms will one mole of Carbon (C-12) contain?

A. \(12 \times 10^{24}\)

B. \(12 \times 10^{23}\)

C. \(6.02 \times 10^{24}\)

D. \(6.02 \times 10^{23}\)

One mole of any substance contains \(6.02 \times 10^{23}\) particles. This number is known as Avogadro's number. Therefore, one mole of carbon (C-12) contains \(6.02 \times 10^{23}\) atoms.

Q73: The elements belonging to the same group of the periodic table have the same ______.

A. Number of neutrons

B. Number of electrons in the outermost shell

C. Number of protons

D. Atomic mass

Elements in the same group of the periodic table have the same number of electrons in their outermost shell. This results in similar chemical properties among the elements in the group.

Q74: Which of the following elements has valency 3?

A. Ca

B. Na

C. Mg

D. Al

Aluminium (Al) has a valency of 3. Valency is the combining capacity of an element, determined by the number of electrons it can lose, gain, or share to form a chemical bond.

Q75: The maximum number of electrons that can be accommodated in M shell is:

A. 8

B. 18

C. 2

D. 32

The M shell (third shell) can accommodate a maximum of 18 electrons. The electronic configuration for a filled M shell is \(3s^2 3p^6 3d^{10}\).

Q76: Dobereiner tried to arrange the element with similar properties into groups. For this he identified some groups having how many elements?

A. 4

B. 6

C. 3

D. 5

Johann Wolfgang Dobereiner arranged elements with similar properties into groups of three, known as triads. This was one of the early attempts to classify elements based on their properties.

Q77: Select the correct Dobereiner’s triads from the given sets.

A. Fe, Co, Ni

B. Ca, Sr, Ba

C. Cl, Br, I

D. Li, Na, K

Calcium (Ca), Strontium (Sr), and Barium (Ba) form a Dobereiner's triad. These elements have similar properties and were grouped together based on their atomic masses and chemical behaviors.

Q78: Who discovered the law of octaves and compared this to the octaves found in music?

A. Henry Moseley

B. Dmitri Mendeleev

C. John Newlands

D. Johann Wolfgang Dobereiner

John Newlands discovered the law of octaves, which stated that when elements are arranged in order of increasing atomic weights, the eighth element is a kind of repetition of the first. He compared this to the octaves found in music.

Q79: Who first discovered that every eighth element had properties similar to that of the first?

A. Dobereiner

B. Newlands

C. Moseley

D. Mendeleev

John Newlands first discovered that every eighth element had properties similar to the first. This observation led to the development of the law of octaves.

Q80: Newlands arranged the elements into the periodic table on the basis of ______.

A. increasing number of protons

B. increasing atomic mass

C. increasing number of electrons

D. increasing atomic number

Newlands arranged the elements into the periodic table based on increasing atomic mass. This was one of the early attempts to organize elements based on their properties.

Q81: In Newlands’s law of the octaves, the first element is ______ and the last known element is______.

A. hydrogen, thorium

B. helium, uranium

C. helium, thorium

D. hydrogen, uranium

In Newlands's law of octaves, the first element is hydrogen, and the last known element at that time was thorium. This law was based on the observation that properties of elements repeat every eighth element, similar to musical octaves.

Q82: Which of the following is the last element in Newlands Law of Octaves classification?

A. Thorium

B. Uranium

C. Radium

D. Actinium

Thorium was the last element in Newlands's law of octaves classification. This law was based on the properties of elements repeating every eighth element, similar to musical octaves.

Q83: Mendeleev’s Periodic Table was published in ______.

A. 1869

B. 1872

C. 1889

D. 1900

Dmitri Mendeleev published his periodic table in 1872. This table was based on the periodic law, which stated that the properties of elements are a periodic function of their atomic masses.

Q84: The credit for classifying the elements on the basis of their atomic masses goes to ______.

A. Dmitri Mendeleev

B. Johann Wolfgang Dobereiner

C. John Newlands

D. Henry Moseley

Dmitri Mendeleev is credited with classifying the elements based on their atomic masses. His periodic table was a significant advancement in the organization of elements.

Q85: Mendeleev’s Periodic Law states that:

A. the properties of elements are the periodic function of their atomic numbers

B. the properties of elements are the periodic function of their atomic masses

C. the properties of elements are the periodic function of their ionization energy

D. the properties of elements are the periodic function of their electronegativity

Mendeleev's Periodic Law states that the properties of elements are a periodic function of their atomic masses. This law led to the development of the periodic table.

Q86: Among chemical properties, Mendeleev concentrated on the compounds formed by the elements with:

A. Nitrogen and Oxygen

B. Hydrogen and Oxygen

C. Carbon and Hydrogen

D. Sulfur and Oxygen

Mendeleev focused on the compounds formed by elements with hydrogen and oxygen to understand their chemical properties and to arrange them in the periodic table.

Q87: How are elements arranged in the Modern Periodic Table?

A. In the increasing order of their Ionization Energy

B. In the increasing order of their Electronegativity

C. In the increasing order of their Atomic Number

D. In the increasing order of their Atomic Mass

In the Modern Periodic Table, elements are arranged in increasing order of their atomic numbers. This arrangement helps in predicting the properties of elements based on their position.

Q88: Which is the first element on the periodic table?

A. Helium

B. Beryllium

C. Lithium

D. Hydrogen

Hydrogen is the first element on the periodic table. It has the atomic number 1, making it the lightest and simplest element.

Q89: The most reactive of the following metals is:

A. Na

B. Al

C. Mg

D. Ca

Calcium (Ca) is the most reactive among the given metals. Its reactivity is due to its low ionization energy and strong tendency to lose electrons to form positive ions.

Q90: The electron distribution in an aluminium atom is:

A. 2, 8, 4

B. 2, 8, 2

C. 2, 8, 1

D. 2, 8, 3

The electron distribution in an aluminium atom is 2, 8, 3. This configuration represents the number of electrons in each shell, with 2 electrons in the first shell, 8 in the second, and 3 in the third.

Q91: ______ is predominantly used for making photovoltaic solar cells.

A. Si

B. Sn

C. Pb

D. Ge

Silicon (Si) is predominantly used for making photovoltaic solar cells. Its semiconductor properties make it ideal for converting sunlight into electrical energy.

Q92: Which elements is represented by the symbol “Si”?

A. Silicon

B. Sodium

C. Silver

D. Sulfur

The symbol "Si" represents silicon, a metalloid element with atomic number 14. It is widely used in semiconductors and electronics.

Q93: What is the atomicity of Phosphorous?

A. Tetra-atomic

B. Diatomic

C. Monoatomic

D. Triatomic

Phosphorus is tetra-atomic, meaning its molecules consist of four atoms. The most common allotrope of phosphorus is white phosphorus, which exists as \(\text{P}_4\) molecules.

Q94: ______ in the air turns silver articles black (when exposed to air).

A. Oxygen

B. Sulphur

C. Carbon dioxide

D. Nitrogen

Sulphur in the air reacts with silver to form a black coating of silver sulfide (\(\text{Ag}_2\text{S}\)). This reaction is responsible for the tarnishing of silver articles when exposed to air.

Q95: The electronic configuration of chlorine is ______.

A. 2, 8, 6

B. 2, 8, 7

C. 2, 8, 8

D. 2, 8, 9

The electronic configuration of chlorine is 2, 8, 7. This configuration represents the number of electrons in each shell, with 2 electrons in the first shell, 8 in the second, and 7 in the third.

Q96: ______ is a greenish yellow gas with a characteristic smell at room temperature.

A. Nitrogen

B. Chlorine

C. Hydrogen

D. Oxygen

Chlorine is a greenish-yellow gas with a characteristic pungent smell at room temperature. It is a highly reactive non-metal and a strong oxidizing agent.

Q97: Which element has the greatest tendency to attract electrons?

A. Bromine

B. Oxygen

C. Chlorine

D. Fluorine

Fluorine has the greatest tendency to attract electrons, making it the most electronegative element in the periodic table. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.

Q98: What is the chemical symbol for Sulphur?

A. Se

B. S

C. Sr

D. Si

The chemical symbol for sulfur is "S". Sulfur is a non-metal element with atomic number 16 and is essential for various industrial and biological processes.

Q99: What is the symbol of the element Tungsten?

A. T

B. W

C. Tu

D. Tg

The symbol for the element tungsten is "W". Tungsten is a metallic element with atomic number 74, known for its high melting point and strength.

Q100: Which of the following metals is most metallic in nature?

A. Cs

B. Al

C. Mg

D. Na

Cesium (Cs) is the most metallic in nature among the given options. It is an alkali metal with the lowest ionization energy, making it highly reactive and metallic.

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