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The correct answer is Statement 1 is false but Statement 2 is true.

Key Points

• The chemical structure CH₃−CH₂−CHO consists of a three-carbon chain with a terminal carbonyl group bonded to a hydrogen atom, identifying it as an aldehyde. Under IUPAC nomenclature, a three-carbon aldehyde is named propanal, whereas propanone is a ketone with the formula CH₃−CO−CH₃. Hence, statement 1 is incorrect.
• The IUPAC system for naming organic compounds dictates that the presence of an aldehyde functional group is indicated by replacing the terminal '-e' of the parent alkane name with the suffix -al. For instance, ethane becomes ethanal and propane becomes propanal. Hence, statement 2 is correct.

 Additional Information

• Aldehydes:
• These are compounds containing the −CHO functional group, where the carbon atom is double-bonded to oxygen and single-bonded to hydrogen.
• The aldehyde group is always located at the terminal position (end) of a carbon chain, meaning the carbon in this group is always assigned carbon-1 in numbering.
• Common examples include methanal (formaldehyde) and ethanal (acetaldehyde), which are used extensively in industrial synthesis.
• Ketones:
• These feature a carbonyl group (C=O) located at a non-terminal position, meaning it is bonded to two other carbon atoms.
• They are named using the suffix -one.
• Propanone, also known as acetone, is the simplest ketone and is widely used as a solvent in laboratory and industrial applications.

The correct answer is Covering unequal distances in equal intervals of time.

Key Points

• Non-uniform motion is defined as the type of motion where an object covers unequal distances in equal intervals of time, indicating that the velocity of the object is not constant.
• In this type of motion, the speed of the object changes at different points during its journey, which means the instantaneous speed fluctuates rather than remaining steady.
• The distance-time graph for an object in non-uniform motion is represented by a curved line, showing that the slope (which represents speed) varies over time.
• Because the velocity (magnitude or direction) is changing, the object is always subjected to acceleration or deceleration.
• A real-world example is a car moving in heavy traffic, where the driver frequently applies brakes and accelerates, causing the car to cover different distances in each consecutive minute.

 Additional Information

• Uniform Motion:
• Characterized by an object covering equal distances in equal intervals of time.
• The velocity remains constant, and the direction of motion does not change.
• The acceleration in uniform motion is strictly zero because there is no change in velocity.
• Its distance-time graph is a straight line with a constant slope.
• Acceleration:
• It is the rate of change of velocity with respect to time, measured in meters per second squared (m/s²).
• Positive acceleration occurs when the speed increases, while negative acceleration (retardation) occurs when the speed decreases.
• In non-uniform motion, acceleration can be uniform (velocity changes at a constant rate) or non-uniform (velocity changes at varying rates).

The correct answer is It is used as a strong acid..

Key Points

• Sodium Hydrogen Carbonate (NaHCO₃), commonly known as baking soda, is used as a leavening agent in baking because it reacts with acidic components to release carbon dioxide gas, which causes dough to rise. Hence, statement 1 is correct.
• Sodium hydrogen carbonate is a basic salt derived from a strong base (NaOH) and a weak acid (H₂CO₃); it has a pH of approximately 8.3 and does not behave as a strong acid. Hence, statement 2 is incorrect.
• It is a crucial component in soda-acid fire extinguishers, where it reacts with an acid to produce a heavy blanket of carbon dioxide gas that cuts off the oxygen supply to the fire. Hence, statement 3 is correct.
• Due to its mildly alkaline nature, it is widely used as an antacid to neutralize the excess hydrochloric acid produced in the stomach, thereby relieving acidity and heartburn. Hence, statement 4 is correct.

 Additional Information

• Sodium Hydrogen Carbonate Characteristics:
• Chemical Formula: NaHCO₃, also referred to as sodium bicarbonate.
• Production: It is manufactured using the Solvay process, involving the reaction of sodium chloride, ammonia, and carbon dioxide in water.
• Decomposition: When heated above 50°C, it decomposes into sodium carbonate (Na₂CO₃), water, and carbon dioxide.
• Strong Acids vs. Weak Bases: Strong acids like HCl or H₂SO₄ fully ionize in water, whereas NaHCO₃ is a weak base used to neutralize such acids in chemical spills and medical applications.

The correct answer is Both statements are false.

Key Points

• Statement 1 suggests that metals and non-metals react by sharing electrons. However, in chemical reactions between these two groups, metals (which have low ionization energy) typically lose electrons to form positive cations, while non-metals (which have high electron affinity) gain those electrons to form negative anions. This process is defined as electron transfer rather than sharing. Hence, statement 1 is incorrect.
• Statement 2 posits that the bond formed between a metal and a non-metal is covalent. A covalent bond involves the mutual sharing of electron pairs, which generally occurs between two non-metals. The bond resulting from the strong electrostatic force of attraction between oppositely charged ions (formed by electron transfer) is known as an ionic bond or electrovalent bond. Hence, statement 2 is incorrect.

 Additional Information

• Ionic Compounds:
• These compounds, such as Sodium Chloride (NaCl) or Magnesium Chloride (MgCl₂), typically exist as crystalline solids.
• They possess high melting and boiling points due to the strong inter-ionic attraction.
• They are generally soluble in polar solvents like water but insoluble in organic solvents like kerosene or petrol.
• They conduct electricity in the molten state or in aqueous solution due to the movement of free ions.
• Covalent Compounds:
• Formed by atoms of non-metals to achieve a stable noble gas configuration.
• Examples include Methane (CH₄), Water (H₂O), and Carbon Dioxide (CO₂).
• These substances usually have low melting and boiling points because the intermolecular forces (like Van der Waals forces) are relatively weak compared to ionic bonds.
• Octet Rule: Atoms tend to gain, lose, or share electrons to have eight electrons in their outermost shell, ensuring maximum chemical stability.

The correct answer is Enlarged, real, inverted.

Key Points

• When an object is positioned between the first principal focus (F₁) and the center of curvature (2F₁) of a convex lens, the rays of light originating from the object undergo refraction to form an image on the opposite side of the lens.
• According to the rules of ray diagrams, a ray incident parallel to the principal axis passes through the second principal focus (F₂) after refraction.
• Another ray passing through the optical center (O) of the convex lens travels straight without any angular deviation.
• These refracted rays actually intersect at a specific point located beyond 2F₂ on the other side, characterizing the image as real and inverted.
• Since the image is formed further away from the lens than the object is (image distance v > object distance u), the linear magnification (m = v/u) is greater than 1, resulting in an enlarged or magnified image.

 Additional Information

• Convex Lens Image Characteristics:
• Object at 2F₁: The image is formed exactly at 2F₂, is real, inverted, and the same size as the object.
• Object beyond 2F₁: The image is formed between F₂ and 2F₂ and is diminished, real, and inverted.
• Object at F₁: The rays emerge parallel after refraction, meaning the image is formed at infinity and is highly enlarged.
• Object between F₁ and Optical Center: This is the only case where a convex lens produces a virtual, erect, and enlarged image, which appears on the same side as the object.
• Thin Lens Formula: The relationship between object distance (u), image distance (v), and focal length (f) is given by 1/f = 1/v − 1/u.

The correct answer is Oxygen has 8 protons and 8 electrons.

Key Points

• The atomic number (represented by the symbol Z) of a chemical element is defined as the total number of protons found in the nucleus of an atom.
• For Oxygen, an atomic number of 8 signifies that every oxygen atom contains exactly 8 protons in its central core.
• In any electrically neutral atom, the number of negatively charged electrons must equal the number of positively charged protons to balance the net charge.
• As a result, a neutral oxygen atom possesses 8 electrons arranged in its electron shells (2 in the first shell and 6 in the second shell).

 Additional Information

• Subatomic Particles and Structure:
• Protons: These are positively charged particles that define the identity of the element. They are located inside the nucleus, not in the orbits.
• Electrons: These are negatively charged particles that move around the nucleus in specific energy levels or orbitals.
• Neutrons: These are uncharged particles located in the nucleus. The number of neutrons is determined by the Mass Number (A) minus the Atomic Number (Z). While the most common isotope of oxygen (Oxygen-16) has 8 neutrons, other isotopes like Oxygen-18 have 10 neutrons.
• Molecular Structure:
• The number of atoms in a molecule is known as atomicity. Oxygen usually exists as a diatomic molecule (O₂), which means it has 2 atoms per molecule, whereas Ozone (O₃) has 3.

The correct answer is CuO + H₂ → Cu + H₂O.

Key Points

• A combination reaction (also known as a synthesis reaction) occurs when two or more reactants (elements or compounds) combine chemically to form a single product. The general form is represented as A + B → AB.
• The reaction NH₃ + HCl → NH₄Cl involves ammonia and hydrogen chloride gas reacting to form a single solid product, ammonium chloride. Since there is only one product, it is a combination reaction.
• In 2Cu + O₂ → 2CuO, elemental copper reacts with oxygen upon heating to produce copper(II) oxide. As multiple reactants form one product, this is a combination reaction.
• The reaction CaO + H₂O → Ca(OH)₂ involves calcium oxide (quicklime) reacting vigorously with water to produce calcium hydroxide (slaked lime). This is a classic example of a combination reaction.
• The equation CuO + H₂ → Cu + H₂O shows copper oxide reacting with hydrogen to produce copper and water. Because there are two distinct products formed, it does not meet the criteria of a combination reaction.

 Additional Information

• Redox and Displacement: The reaction CuO + H₂ → Cu + H₂O is categorized as a Redox Reaction.
• Reduction: The CuO is reduced to Cu because it loses oxygen.
• Oxidation: The H₂ is oxidized to H₂O because it gains oxygen.
• Displacement: This can also be viewed as a displacement reaction where hydrogen displaces copper from its oxide due to the reactivity series.
• Exothermic Nature: Many combination reactions, such as the formation of slaked lime, are highly exothermic, releasing significant amounts of thermal energy during the process.

The correct answer is It has a very high melting point..

Key Points

• Tungsten, also known as Wolfram, is used for bulb filaments because it possesses the highest melting point of any pure metal, recorded at approximately 3422 degrees Celsius.
• Incandescent bulbs operate by heating a filament to extremely high temperatures (around 2500 degrees Celsius) so that it glows and emits visible light; tungsten can withstand this heat without melting or losing structural integrity.
• The metal exhibits very low vapor pressure at high temperatures, which minimizes the rate of sublimation and prevents the filament from thinning out too quickly during operation.
• Tungsten has high tensile strength, allowing it to be drawn into extremely thin coiled wires that are durable enough to survive the mechanical stresses within a glass envelope.
• Its resistivity is sufficient to generate the necessary heat energy through Joule heating (H = I²Rt) when an electric current passes through the thin wire.

 Additional Information

• Inert Gas Filling:
• To prevent the filament from oxidizing at high temperatures, bulbs are filled with chemically inactive gases such as Argon or Nitrogen.
• This environment suppresses tungsten evaporation, thereby increasing the lifespan of the electric bulb.
• Properties of Tungsten:
• Atomic Number: It has an atomic number of 74 and belongs to the d-block of the periodic table.
• Thermal Conductivity: It possesses good thermal conductivity, which helps in the distribution of heat along the filament length.
• Efficiency: While effective, tungsten bulbs are less efficient than LEDs as most energy is lost as Infrared radiation (heat) rather than light.

The correct answer is Sodium donates one electron to chlorine, forming oppositely charged ions held by strong electrostatic forces..

Key Points

• Sodium (Na), with an atomic number of 11, has a single valence electron ([Ne] 3s¹) which it donates to Chlorine (Cl) to achieve a stable Octet, resulting in the formation of Na⁺ and Cl⁻ ions bonded by Coulombic attraction. Hence, statement 1 is correct.
• Covalent bonds are formed by the mutual sharing of electron pairs between atoms, typically occurring between non-metals with low electronegativity differences, which does not characterize the metal-nonmetal bond in NaCl. Hence, statement 2 is incorrect.
• A metallic lattice consists of metal cations surrounded by a sea of delocalized electrons; this structure is found in pure Sodium metal but is replaced by an ionic crystal structure once the reaction with Chlorine occurs. Hence, statement 3 is incorrect.
• In this redox reaction, Sodium undergoes oxidation by losing an electron to become a positive cation, while Chlorine undergoes reduction by gaining that electron; sodium never gains electrons from chlorine. Hence, statement 4 is incorrect.

 Additional Information

• Ionic Bond Stability:
• Octet Rule: The transfer allows both atoms to reach the electronic configuration of Noble Gases (Neon for Sodium and Argon for Chlorine).
• Lattice Energy: The stability is significantly enhanced by the Lattice Energy, which is the energy released when gaseous ions pack together to form a solid ionic crystal.
• Crystal Structure: Sodium Chloride forms a Face-Centered Cubic (FCC) lattice where each ion is coordinated by six ions of the opposite charge.
• Electronegativity: The large difference in Electronegativity (Sodium ≈ 0.9, Chlorine ≈ 3.0) ensures that the bond is purely Ionic rather than covalent.

The correct answer is 200 kg.

Key Points

• Identify the given physical quantities: The Unbalanced Force (F) is 100 N, the Initial Velocity (u) is 0 m/s (since the body is at rest), the Final Velocity (v) is 5 m/s, and the Time Interval (t) is 10 s.
• Calculate the Acceleration (a) of the body using the first equation of motion or the definition of acceleration, which is the rate of change of velocity. The formula is a = (v − u) / t.
• Substituting the values: a = (5 − 0) / 10, which results in a = 0.5 m/s².
• Apply Newton's Second Law of Motion, which mathematically states that Force (F) = Mass (m) × Acceleration (a).
• To find the Mass (m), rearrange the formula to m = F / a.
• Substituting the known values into the equation: m = 100 / 0.5. This calculation yields a result of 200 kg.

 Additional Information

• Newton's Second Law of Motion:
• It establishes a quantitative relationship between Force, Mass, and Acceleration.
• The law states that the acceleration of an object is directly proportional to the Net Force acting on it and inversely proportional to its Mass.
• The SI unit of force is the Newton (N), which is equivalent to 1 kg·m/s².
• Inertia and Mass:
• Mass is a fundamental property of matter that quantifies the amount of Inertia an object possesses.
• Higher mass results in greater resistance to changes in the state of Motion or Rest.
• Unlike weight, mass is a Scalar Quantity and remains constant regardless of gravitational changes.