9th science half yearly question paper 2019

The half-yearly question paper for 9th science in 2019 included various important topics, ensuring comprehensive coverage of the syllabus. Students needed to answer multiple-choice, short-answer, and long-answer questions. Preparing for such papers requires understanding the concepts and practicing questions to strengthen knowledge. Below are questions and answers from all sections of the paper for thorough preparation.

Physics Section

Question: What is the SI unit of force?

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

Question: State Newton’s first law of motion.

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

Question: Define velocity.

Answer: Velocity is the speed of an object in a specific direction.

Question: What is the formula for calculating work?

Answer: Work is calculated using the formula: Work = Force × Displacement × cos(θ).

Question: Explain the concept of acceleration.

Answer: Acceleration is the rate at which an object changes its velocity over time.

Question: What is inertia?

Answer: Inertia is the property of an object to resist changes in its state of motion or rest.

Question: State the law of conservation of energy.

Answer: Energy can neither be created nor destroyed; it can only change from one form to another.

Question: What is the unit of energy in the SI system?

Answer: The SI unit of energy is the joule (J).

Question: Define power.

Answer: Power is the rate at which work is done or energy is transferred.

Question: Write the formula for gravitational force.

Answer: Gravitational force is calculated as: F = G × (m1 × m2) / r².

Question: What is a simple machine?

Answer: A simple machine is a mechanical device that changes the direction or magnitude of a force.

Question: What is kinetic energy?

Answer: Kinetic energy is the energy possessed by an object due to its motion.

Question: Define potential energy.

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

Question: What is the speed of light in a vacuum?

Answer: The speed of light in a vacuum is approximately 3 × 10⁸ m/s.

Question: What is friction?

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

Question: How is pressure defined?

Answer: Pressure is defined as force applied per unit area.

Question: State the principle of moments.

Answer: The principle of moments states that for an object in equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments.

Question: What is a scalar quantity?

Answer: A scalar quantity is one that has only magnitude and no direction.

Question: What is a vector quantity?

Answer: A vector quantity has both magnitude and direction.

Question: What is the formula for calculating density?

Answer: Density is calculated as: Density = Mass / Volume.

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Chemistry Section

Question: What is the atomic number of oxygen?

Answer: The atomic number of oxygen is 8.

Question: Define isotopes.

Answer: Isotopes are atoms of the same element with the same atomic number but different mass numbers.

Question: What is the chemical formula for water?

Answer: The chemical formula for water is H₂O.

Question: Name the process of separating a mixture using evaporation.

Answer: The process is called evaporation or vaporization.

Question: What is the pH scale?

Answer: The pH scale measures the acidity or basicity of a solution.

Question: What is the molar mass of carbon dioxide (CO₂)?

Answer: The molar mass of CO₂ is 44 g/mol.

Question: Define a chemical reaction.

Answer: A chemical reaction is a process in which substances interact to form new substances with different properties.

Question: What is the valency of hydrogen?

Answer: The valency of hydrogen is 1.

Question: What is an acid?

Answer: An acid is a substance that donates hydrogen ions (H⁺) in a solution.

Question: What is a base?

Answer: A base is a substance that accepts hydrogen ions (H⁺) or donates hydroxide ions (OH⁻).

Question: What is a salt?

Answer: A salt is a compound formed from the reaction of an acid and a base.

Question: What is an exothermic reaction?

Answer: An exothermic reaction is one that releases heat to the surroundings.

Question: What is an endothermic reaction?

Answer: An endothermic reaction absorbs heat from the surroundings.

Question: Define an element.

Answer: An element is a pure substance made of only one type of atom.

Question: Define a compound.

Answer: A compound is a substance formed by the chemical combination of two or more elements in fixed proportions.

Question: What is electrolysis?

Answer: Electrolysis is the process of breaking down a compound into its elements using electricity.

Question: Name a method to purify water.

Answer: Water can be purified by distillation.

Question: What is oxidation?

Answer: Oxidation is the process of losing electrons or gaining oxygen in a chemical reaction.

Question: What is reduction?

Answer: Reduction is the process of gaining electrons or losing oxygen in a chemical reaction.

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Biology Section

Question: What is photosynthesis?

Answer: Photosynthesis is the process by which green plants use sunlight, carbon dioxide, and water to produce glucose and oxygen.

Question: What is the basic unit of life?

Answer: The basic unit of life is the cell.

Question: Define osmosis.

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

Question: What is a tissue?

Answer: A tissue is a group of cells that perform a similar function.

Question: Name the powerhouse of the cell.

Answer: The powerhouse of the cell is the mitochondrion.

Question: What is the function of chloroplasts?

Answer: Chloroplasts are responsible for photosynthesis in plant cells.

Question: What is the role of hemoglobin in the body?

Answer: Hemoglobin transports oxygen from the lungs to the tissues and carries carbon dioxide back to the lungs.

Question: Define transpiration.

Answer: Transpiration is the process of water loss from plants through small openings called stomata.

Question: What is a vertebrate?

Answer: A vertebrate is an animal with a backbone or spinal column.

Question: What is an invertebrate?

Answer: An invertebrate is an animal without a backbone.

Question: Name the largest organ in the human body.

Answer: The largest organ in the human body is the skin.

Question: What is a neuron?

Answer: A neuron is a nerve cell that transmits electrical signals in the body.

Question: Define an ecosystem.

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

Question: What is biodiversity?

Answer: Biodiversity refers to the variety of life forms within an ecosystem or on Earth.

Question: What is a food chain?

Answer: A food chain is a linear sequence showing the transfer of energy through various organisms by eating and being eaten.

Question: Define a food web.

Answer: A food web is a complex network of interconnected food chains in an ecosystem.

Question: What is a habitat?

Answer: A habitat is the natural environment where an organism lives and thrives.

Question: What is pollination?

Answer: Pollination is the transfer of pollen from the male part of a flower to the female part to enable fertilization.

Question: What is fertilization in biology?

Answer: Fertilization is the process where male and female gametes fuse to form a zygote.