Science and Technology Maharashtra State Board Standard Ten Part-1

Chapter 1: Gravitation

• Discovery of Gravitation:

  • Discovered by Sir Isaac Newton after observing an apple fall vertically from a tree.

  • Newton concluded the Earth attracts objects toward its center. This force is directed along the perpendicular from the object to the surface of the earth.

  • Theory extends to far objects like the Moon, planets, and the Sun.

• Force and Motion:

  • A force is required to change both the speed and the direction of an object's motion.

• Circular Motion and Centripetal Force:

  • Centripetal Force: A force acting on any object moving along a circle, directed toward the center of the circle. "Centripetal" means "center-seeking."

  • Without this force, an object (like a stone on a string) flies off along a straight line tangent to the circle at the point of release.

  • The Moon revolves around the Earth because the Earth exerts a centripetal force of attraction on it.

• Kepler’s Laws of Planetary Motion:

  • Kepler’s First Law: The orbit of a planet is an ellipse with the Sun at one of the two foci.

  • Kepler’s Second Law: The line joining the planet and the Sun sweeps equal areas in equal intervals of time ($\text{Area ASB} = \text{Area CSD} = \text{Area ESF}$).

  • Kepler’s Third Law: The square of the period of revolution ($T$) is directly proportional to the cube of the mean distance ($r$) from the Sun.

  • Mathematical form: $\frac{T^2}{r^3} = K$ (constant).

• Newton’s Universal Law of Gravitation:

  • Every object in the universe attracts every other object with a force directly proportional to the product of their masses ($m_1, m_2$) and inversely proportional to the square of the distance ($d$) between them.

  • Formula: $F = \frac{G m_1 m_2}{d^2}$.

  • Universal Gravitational Constant ($G$): Value first measured by Henry Cavendish as $6.673 \times 10^{-11} \text{N m}^2 \text{kg}^{-2}$.

  • If mass is doubled, force doubles; if distance is doubled, force decreases by a factor of 4.

• Acceleration Due to Gravity ($g$):

  • The gravitational force results in the acceleration of an object toward the center of the Earth.

  • Standard value on Earth's surface: $g = \frac{GM}{R^2} \text{ (approx. } 9.77 \text{ m/s}^2 \text{ or } 9.8 \text{ m/s}^2)$.

  • Variation in $g$:

    • Along the surface: Highest at the poles ($9.832 \text{ m/s}^2$) because the Earth is flatter there; lowest at the equator ($9.78 \text{ m/s}^2$) due to the bulge.

    • With height: $g$ decreases as distance from the center increases (e.g., at $35,700 \text{ km}$, $g = 0.225 \text{ m/s}^2$).

    • With depth: $g$ decreases toward the center of the Earth because the mass ($M$) contributing to gravity effectively decreases.

• Mass vs. Weight:

  • Mass: Amount of matter in an object; scalar; constant everywhere; SI unit is kg.

  • Weight: Force with which Earth attracts the object ($W = mg$); vector directed toward Earth's center; changes with location; SI unit is Newton.

• Free Fall:

  • Occurs when an object moves solely under the influence of gravity ($u=0$).

  • Equations of motion for free fall: $v = gt$, $s = \frac{1}{2} gt^2$, $v^2 = 2gs$.

  • True free fall is possible only in a vacuum.

• Escape Velocity ($v_{esc}$):

  • The minimum initial velocity required for an object to overcome Earth's gravitational pull and escape to infinite distance.

  • Formula: $v_{esc} = \frac{\sqrt{2GM}}{R} = \sqrt{2gR}$.

  • On Earth, $v_{esc} \text{ is approx. } 11.2 \text{ km/s}$. On the Moon, it is approx. $2.37 \text{ km/s}$.

Chapter 2: Periodic Classification of Elements

• Historical Attempts at Classification:

  • Dobereiner’s Triads (1817): Groups of three elements where the atomic mass of the middle element was approximately the mean of the other two (e.g., Li, Na, K).

  • Newlands’ Law of Octaves (1866): Arranged by atomic mass; every eighth element had properties similar to the first (like musical notes). Applicable only up to Calcium.

  • Mendeleev’s Periodic Table (1869-1872):

    • Law: Properties of elements are a periodic function of their atomic masses.

    • Organized 63 known elements into groups (vertical) and periods (horizontal).

    • Merits: Revised atomic masses (e.g., Beryllium from 14.09 to 9.4); left gaps for undiscovered elements (Eka-boron, Eka-aluminum, Eka-silicon).

    • Demerits: Ambiguity for Cobalt and Nickel; no place for isotopes; no fixed position for Hydrogen.

• Modern Periodic Law (Henry Moseley, 1913):

  • Properties of elements are a periodic function of their atomic numbers ($Z$).

• Structure of the Modern Periodic Table:

  • 118 elements arranged in 7 periods and 18 groups.

  • Blocks:

    • s-block: Groups 1 and 2.

    • p-block: Groups 13 to 18 (includes metals, nonmetals, and metalloids along a zig-zag line).

    • d-block: Groups 3 to 12 (Transition elements).

    • f-block: Lanthanide and Actinide series at the bottom.

• Periodic Trends:

  • Valency: Determined by valence electrons. Remains same in a group; increases then decreases across a period (1 to 4 to 0).

  • Atomic Size: Indicated by atomic radius (measured in picometers, $1 \text{ pm} = 10^{-12} \text{ m}$).

    • Down a group: Increases (new shells added).

    • Across a period: Decreases (increased nuclear charge pulls electrons closer).

  • Metallic Character (Electropositivity): Tendency to lose electrons.

    • Down a group: Increases.

    • Across a period: Decreases.

  • Nonmetallic Character (Electronegativity): Tendency to gain electrons.

    • Down a group: Decreases.

    • Across a period: Increases.

Chapter 3: Chemical Reactions and Equations

• Basic Concepts:

  • Reactants: Substances undergoing bond breaking at the start.

  • Products: New substances formed by new bonds.

  • Physical Change: Temporary/reversible; composition remains same (e.g., Ice melting).

  • Chemical Change: Permanent; composition changes.

• Writing Chemical Equations:

  • Reactants on left, products on right, separated by an arrow ($\rightarrow$).

  • Physical states: $(g)$, $(l)$, $(s)$, $(aq)$. Precipitates shown with $\downarrow$, gases with $\uparrow$.

  • Heat absorbed indicated by $\Delta$; heat released written as "+ Heat".

• Types of Chemical Reactions:

  • Combination: Two or more reactants form a single product ($A + B \rightarrow AB$).

  • Decomposition: A single reactant breaks down into two or more products ($AB \rightarrow A + B$).

    • Thermal (using heat); Electrolysis (using electricity).

  • Displacement: A more reactive element takes the place of a less reactive element in a compound.

  • Double Displacement: Exchange of ions between reactants to form a precipitate.

  • Exothermic: Heat is given out (e.g., $CaO + H_2O \rightarrow Ca(OH)_2 + \text{Heat}$).

  • Endothermic: Heat is absorbed (e.g., $CaCO_3 + \text{Heat} \rightarrow CaO + CO_2$).

• Factors Affecting Rate of Reaction:

  • Nature of Reactants: More reactive metals react faster.

  • Particle Size: Smaller particles have larger surface area, increasing the rate.

  • Concentration: Concentrated reactants react faster than dilute ones.

  • Temperature: Rate increases with increasing temperature.

  • Catalyst: A substance that increases the reaction rate without undergoing a chemical change (e.g., $MnO_2$ for decomposition of $H_2O_2$).

• Oxidation and Reduction:

  • Oxidation: Gaining oxygen, losing hydrogen, or losing electrons.

  • Reduction: Gaining hydrogen, losing oxygen, or gaining electrons.

  • Redox Reaction: Simultaneous oxidation and reduction.

• Corrosion and Rancidity:

  • Corrosion: Damage to metals due to environmental factors. Rusting of iron requires both air and water. Formula for rust: $Fe_2O_3 \times H_2O$.

  • Rancidity: Foul odor/taste in old cooking oil due to air oxidation. Prevented by antioxidants or airtight storage.

Chapter 4: Effects of Electric Current

• Heating Effect:

  • Joule’s Law of Heating: The heat produced ($H$) in a resistor is proportional to the square of current ($I$), resistance ($R$), and time ($t$): $H = I^2 Rt$.

  • Electrical Power ($P$): $P = V \times I = I^2 R = \frac{V^2}{R}$. Unit: Watt ($W$).

  • Commercial Unit: $1 \text{ kWh (unit)} = 3.6 \times 10^6 \text{ J}$.

  • Safety Devices: Fuse wire (melts during high current) and MCB (Miniature Circuit Breaker).

• Magnetic Effect:

  • Hans Christian Oersted (1820) discovered that current-carrying wires produce magnetic fields.

  • Right Hand Thumb Rule: Thumb points to current, curled fingers show direction of magnetic lines of force.

  • Magnetic Field in a Solenoid: A copper wire wound in a chain of loops. The field inside is uniform and parallel to the axis.

  • Force on Conductor: A current-carrying conductor in a magnetic field experiences a force.

    • Fleming’s Left Hand Rule: Used for motors. Thumb (Force), Index finger (Magnetic Field), Middle finger (Current) are mutually perpendicular.

• Electric Motor: Device converting electrical energy to mechanical energy using a split ring to reverse current every half rotation.

• Electromagnetic Induction (Faraday):

  • Moving a magnet near a coil or changing current in a primary coil induces a current in a secondary coil.

  • Fleming’s Right Hand Rule: Used for generators. Thumb (Motion), Index (Magnetic Field), Middle (Induced Current).

• Electric Generator:

  • AC Generator: Produces current that changes direction periodically (50 Hz once per second in India).

  • DC Generator: Uses a split ring (commutator) to produce current flowing in one direction in the external circuit.

Chapter 5: Heat

• Latent Heat:

  • Latent Heat of Fusion: Heat absorbed at constant temperature to change solid to liquid.

  • Latent Heat of Vaporization: Heat absorbed at constant temperature to change liquid to gas.

• Regelation: The phenomenon where ice melts under pressure and refreezes when pressure is removed.

• Anomalous Behavior of Water:

  • Between $0 \text{ } ^\text{o}\text{C}$ and $4 \text{ } ^\text{o}\text{C}$, water contracts instead of expanding when heated. Volume is minimum and density is maximum at $4 \text{ } ^\text{o}\text{C}$.

  • Studied using Hope’s Apparatus.

• Humidity:

  • Absolute Humidity: Mass of vapor per unit volume of air ($\text{kg/m}^3$).

  • Relative Humidity: Ratio of actual vapor mass to saturated vapor mass for the same volume and temperature. If $>60\%$, air is humid; if $<60\%$, air is dry.

  • Dew Point: The temperature at which air becomes saturated with vapor.

• Specific Heat Capacity ($c$):

  • Amount of heat required to raise the temperature of unit mass of an object by $1 \text{ } ^\text{o}\text{C}$.

  • Heat exchanged: $Q = m \times c \times \text{ } \Delta T$.

  • Principle of Heat Exchange: Heat lost by hot object = Heat gained by cold object (in an isolated system).

Chapter 6: Refraction of Light

• Laws of Refraction:

  • The incident ray, refracted ray, and normal lie in the same plane.

  • Snell’s Law: For a pair of media, $\frac{\sin(i)}{\sin(r)} = \text{constant} = n$ (refractive index).

• Refractive Index ($n$):

  • Depends on the velocity of light in the media: $_{1}n_{2} = \frac{v_1}{v_2}$.

  • Absolute refractive index: When the first medium is a vacuum ($1.0003$ for air, $2.42$ for diamond).

• Atmospheric Refraction:

  • Twinkling of Stars: Due to changing air density and refractive index causing the apparent position and brightness of stars to flicker.

  • Mirage: Illusion of water on hot roads due to lower refractive index of hot air near the ground.

  • Advanced Sunrise/Delayed Sunset: Sun is visible below the horizon due to atmospheric refraction.

• Dispersion of Light: Separation of white light into its component colors (VIBGYOR) through a prism. Red bends the least (longest wavelength); Violet bends the most (shortest wavelength).

• Total Internal Reflection: When the angle of incidence exceeds the critical angle, light reflects back into the denser medium.

Chapter 7: Lenses

• Types: Convex (converging) and Concave (diverging).

• Lens Formula: $\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$.

• Magnification ($M$): $M = \frac{h_2}{h_1} = \frac{v}{u}$.

• Power of a Lens ($P$): $P = \frac{1}{f} \text{ (in meters)}$. Unit: Dioptre ($D$).

• Human Eye:

  • Anatomy: Cornea, Iris, Pupil, Crystalline Lens, Retina, Optic Nerve.

  • Power of Accommodation: Ability of the lens to change focal length to see objects at various distances.

  • Defects of Vision:

    • Nearsightedness (Myopia): Can't see distant objects; corrected with Concave lenses.

    • Farsightedness (Hypermetropia): Can't see nearby objects; corrected with Convex lenses.

    • Presbyopia: Aging-related loss of accommodation; corrected with bifocal lenses.

Chapter 8: Metallurgy

• Reactivity Series: Arrangement of metals in order of decreasing reactivity (K, Na, Li, Ca… Au).

• Ionic Compounds: Compounds like $NaCl$ with high melting points, crystalline structure, water solubility, and electrical conductivity in molten/dissolved states.

• Extraction of Metals:

  • Concentration: Separation of gangue from ore (Wilfley table, Magnetic separation, Froth floatation, Leaching).

  • Extraction of Aluminum: From Bauxite ore ($Al_2O_3 \times nH_2O$) via Bayer’s/Hall’s process and Electrolytic reduction.

• Corrosion Prevention: Galvanizing (Zinc), Tinning (Tin), Anodization (Oxide layer), Electroplating, and Alloying (e.g., Stainless Steel).

Chapter 9: Carbon Compounds

• Covalent Bonding: Carbon forms four covalent bonds (tetravalency) by sharing electrons.

• Versatility: Catenation (forming long chains) and Isomerism (same formula, different structure).

• Hydrocarbons:

  • Saturated: Alkanes (single bonds, $C_n H_{2n+2}$).

  • Unsaturated: Alkenes (double bond, $C_n H_{2n}$) and Alkynes (triple bond, $C_n H_{2n-2}$).

• Functional Groups: Halo ($-X$), Alcohol ($-OH$), Aldehyde ($-CHO$), Ketone ($-CO-$), Carboxylic Acid ($-COOH$).

• Homologous Series: Series of compounds with the same functional group differing by a $-CH_2-$ unit.

• IUPAC Nomenclature: Prefix-Parent-Suffix system for unique naming.

• Ethanol ($CH_3CH_2OH$): Used as solvent/fuel; oxidizes to Ethanoic Acid ($CH_3COOH$).

• Polymers: Macromolecules formed from repeating units (monomers) (e.g., Polyethylene from Ethylene).

Chapter 10: Space Missions

• Categories: Artificial satellites orbiting Earth and missions to outer space.

• Orbits:

  • High Earth Orbit (HEO): $> 35,780 \text{ km}$; includes Geosynchronous satellites.

  • Medium Earth Orbit (MEO): $2,000 - 35,780 \text{ km}$; used for GPS.

  • Low Earth Orbit (LEO): $180 - 2,000 \text{ km}$; used for ISS and Hubble telescope.

• Satellite Launch Vehicles: PSLV (Polar) and GSLV (Geosynchronous) developed by ISRO.

• Escape Velocity: Needed to bypass Earth's gravity ($11.2 \text{ km/s}$).

• India’s Missions: Chandrayaan-1 (discovered water on Moon) and Mangalyaan (Mars Orbiter Mission).