class 9 half yearly question paper science 2019

Class 9 Half Yearly Question Paper Science 2019

Half-yearly exams are an essential milestone in a student’s academic year. For Class 9 Science, understanding key concepts, solving various questions, and revising effectively is crucial. This guide covers important questions and answers from the 2019 half-yearly science paper, focusing on Physics, Chemistry, and Biology topics to help students prepare efficiently.

Physics

Question: Define motion.

Answer: Motion is the change in position of an object with respect to a reference point over time.

Question: State Newton’s first law of motion.

Answer: Newton’s first law states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.

Question: What is the formula for calculating acceleration?

Answer: Acceleration = (Final velocity – Initial velocity) / Time.

Question: Define inertia.

Answer: Inertia is the property of an object by which it resists changes to its state of rest or motion.

Question: What is the SI unit of force?

Answer: The SI unit of force is the newton (N).

Question: Explain the term “uniform circular motion.”

Answer: Uniform circular motion is the motion of an object moving at a constant speed along a circular path.

Question: State the law of conservation of momentum.

Answer: The law of conservation of momentum states that the total momentum of a closed system remains constant if no external force acts on it.

Question: Write the formula for work.

Answer: Work = Force × Displacement × cos(θ).

Question: What is power?

Answer: Power is the rate of doing work or the rate of transfer of energy.

Question: Define potential energy and give its formula.

Answer: Potential energy is the energy possessed by an object due to its position or configuration. Formula: PE = mgh.

Question: What are non-contact forces?

Answer: Non-contact forces are forces that act on an object without any physical contact, such as gravitational force, magnetic force, and electrostatic force.

Question: Explain the term “gravitational force.”

Answer: Gravitational force is the force of attraction between any two objects with mass.

Question: Write the formula for calculating speed.

Answer: Speed = Distance / Time.

Question: What is kinetic energy?

Answer: Kinetic energy is the energy possessed by an object due to its motion. Formula: KE = 1/2 mv².

Question: Define displacement.

Answer: Displacement is the shortest distance between the initial and final position of an object, along with the direction.

Question: What is the acceleration due to gravity on Earth?

Answer: The acceleration due to gravity on Earth is approximately 9.8 m/s².

Question: State Archimedes’ principle.

Answer: Archimedes’ principle states that a body submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced.

Question: What is the difference between mass and weight?

Answer: Mass is the measure of the amount of matter in an object, whereas weight is the force exerted by gravity on that object.

Question: Define friction.

Answer: Friction is the force that opposes the relative motion or tendency of motion between two surfaces in contact.

Chemistry

Question: What are atoms?

Answer: Atoms are the smallest units of matter that retain the properties of an element.

Question: State the law of conservation of mass.

Answer: The law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction.

Question: What is a chemical formula?

Answer: A chemical formula represents the elements in a compound and the ratio of their atoms.

Question: Define valency.

Answer: Valency is the combining capacity of an element to form chemical bonds.

Question: What are isotopes?

Answer: Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

Question: What is the periodic table?

Answer: The periodic table is an arrangement of elements in order of increasing atomic number, grouped by similar chemical properties.

Question: What is a molecule?

Answer: A molecule is a group of two or more atoms chemically bonded together.

Question: State Dalton’s atomic theory.

Answer: Dalton’s atomic theory states that all matter is composed of indivisible atoms, atoms of the same element are identical, and compounds are formed by a combination of atoms.

Question: Define acids.

Answer: Acids are substances that release hydrogen ions (H⁺) in an aqueous solution.

Question: What is pH?

Answer: pH is a scale used to measure the acidity or basicity of a solution, ranging from 0 to 14.

Question: Define covalent bond.

Answer: A covalent bond is a chemical bond formed by the sharing of electrons between atoms.

Question: What is an ionic bond?

Answer: An ionic bond is a chemical bond formed by the transfer of electrons from one atom to another.

Question: Explain the term “neutralization reaction.”

Answer: Neutralization is a chemical reaction in which an acid and a base react to form salt and water.

Question: What is an alloy?

Answer: An alloy is a mixture of two or more metals, or a metal and a non-metal, to enhance its properties.

Question: Define the term “catalyst.”

Answer: A catalyst is a substance that speeds up a chemical reaction without being consumed.

Question: What is electrolysis?

Answer: Electrolysis is the process of breaking down a compound into its components by passing an electric current through it.

Question: Define hydrocarbons.

Answer: Hydrocarbons are organic compounds made up of hydrogen and carbon atoms.

Question: What is the octet rule?

Answer: The octet rule states that atoms tend to combine in such a way that each atom has eight electrons in its outermost shell.

Question: Write the formula for calculating molarity.

Answer: Molarity = Moles of solute / Volume of solution in liters.

Biology

Question: What are cells?

Answer: Cells are the basic structural and functional units of all living organisms.

Question: Define osmosis.

Answer: Osmosis is the movement of water molecules through a semi-permeable membrane from a region of lower solute concentration to higher solute concentration.

Question: What is photosynthesis?

Answer: Photosynthesis is the process by which green plants use sunlight to synthesize food from carbon dioxide and water.

Question: Define respiration.

Answer: Respiration is the biological process of breaking down glucose to release energy.

Question: What are the components of the nucleus?

Answer: The nucleus consists of the nuclear membrane, nucleoplasm, chromosomes, and nucleolus.

Question: Explain the term “tissue.”

Answer: Tissue is a group of similar cells that perform a specific function in an organism.

Question: What is an ecosystem?

Answer: An ecosystem is a community of living organisms interacting with their physical environment.

Question: Define biodiversity.

Answer: Biodiversity refers to the variety of living organisms in a particular habitat or on Earth.

Question: What are stomata?

Answer: Stomata are small openings on the surface of leaves that allow gas exchange and transpiration.

Question: Explain the term “hormones.”

Answer: Hormones are chemical messengers secreted by glands that regulate various functions in the body.

Question: Define excretion.

Answer: Excretion is the process of removing waste products from the body.

Question: What is a food chain?

Answer: A food chain is a sequence of organisms through which energy and nutrients flow, starting with producers and ending with top predators.

Question: What are decomposers?

Answer: Decomposers are organisms that break down dead organic matter into simpler substances.

Question: Define the term “adaptation.”

Answer: Adaptation is a characteristic that enables an organism to survive and reproduce in its environment.

Question: What is mitosis?

Answer: Mitosis is a type of cell division that results in two identical daughter cells.

Question: Explain the role of the heart in the circulatory system.

Answer: The heart pumps blood throughout the body, supplying oxygen and nutrients while removing waste.

Question: What is the difference between autotrophs and heterotrophs?

Answer: Autotrophs make their own food through processes like photosynthesis, while heterotrophs depend on other organisms for food.

Question: Define pollution.

Answer: Pollution is the contamination of the environment by harmful substances.

Question: What is the function of chlorophyll?

Answer: Chlorophyll absorbs sunlight, enabling plants to perform photosynthesis.