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Oita Public High School Entrance Examination - Science study materials
Oita Public High School Entrance Examination - Science study resources

Oita Public High School Entrance Examination - Science practice questions

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Question 1Physics: measurements, energy and circuits

A train travels 240 km in 2 hours at a constant speed. What is its speed?

  1. 480 km/h
  2. 120 km/h Correct answer.
  3. 60 km/h
  4. 240 km/h

Explanation

Speed equals distance divided by time. Here, 240 km divided by 2 h gives 120 km/h.

Question 2Physics: measurements, energy and circuits

A force of 15 N is applied to a sled, moving it 4 m in the direction of the force. How much work (仕事) is done?

  1. 11 J
  2. 19 J
  3. 3.75 J
  4. 60 J Correct answer.

Explanation

Work equals force times distance moved in the direction of the force. Fifteen N times 4 m equals 60 J.

Question 3Physics: measurements, energy and circuits

A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (Ohm's law, オームの法則)?

  1. 6 V Correct answer.
  2. 0.67 V
  3. 1.5 V
  4. 5 V

Explanation

By Ohm's law, voltage equals current times resistance (V = IR). Two A times 3 Ω equals 6 V.

Question 4Physics: measurements, energy and circuits

Two resistors are connected in series (直列) in the same single loop. Which statement about the current is correct?

  1. Current is zero in a series circuit
  2. Current splits between the two resistors
  3. Current is the same at every point in the loop Correct answer.
  4. Current is largest through the smaller resistor

Explanation

In a series circuit there is only one path, so the same current flows through every component. Current does not split because there are no branches.

Question 5Physics: measurements, energy and circuits

Two resistors are connected in parallel (並列) across a battery. Which statement about the voltage is correct?

  1. Voltage is largest across the larger resistor
  2. Voltage is the same across each branch Correct answer.
  3. Voltage is zero across each resistor
  4. Voltage is largest across the smaller resistor

Explanation

In a parallel circuit each branch connects directly to the same two points of the battery, so the same voltage appears across every branch.

Question 6Physics: measurements, energy and circuits

A 100 V appliance draws 2 A of current. What is its power consumption (電力)?

  1. 50 W
  2. 0.02 W
  3. 102 W
  4. 200 W Correct answer.

Explanation

Electric power equals voltage times current (P = VI). One hundred V times 2 A equals 200 W.

Question 7Physics: measurements, energy and circuits

A 600 W electric kettle is used for 5 minutes. How much electrical energy (電力量) does it consume?

  1. 3,000 J
  2. 180,000 J Correct answer.
  3. 45,000 J
  4. 120 J

Explanation

Electrical energy in joules is power in watts multiplied by time in seconds. Five minutes is 300 s, so 600 W times 300 s equals 180,000 J.

Question 8Physics: measurements, energy and circuits

A force of 40 N is spread evenly over an area of 0.05 m². What is the pressure (圧力)?

  1. 40 Pa·m²
  2. 0.8 Pa
  3. 2 Pa
  4. 800 Pa Correct answer.

Explanation

Pressure equals force divided by area (P = F/A). Forty N divided by 0.05 m² equals 800 Pa.

Question 9Physics: measurements, energy and circuits

Why does a knife with a sharp edge cut more easily than one with a blunt edge, for the same push force?

  1. The sharp knife automatically uses less force
  2. The sharp knife is heavier
  3. The sharp knife is always colder
  4. The smaller contact area gives a larger pressure Correct answer.

Explanation

Pressure equals force divided by area. A smaller contact area means larger pressure for the same force, so the edge penetrates more easily.

Question 10Physics: measurements, energy and circuits

A cart (台車) starts from rest and rolls down a slope. It records positions of 0.5 m after 1 s, 2.0 m after 2 s, and 4.5 m after 3 s. What can you conclude about the cart's motion?

  1. It is decelerating (slowing down)
  2. It is accelerating (speeding up) Correct answer.
  3. It is moving at constant speed
  4. It is stationary

Explanation

The distances (0.5, 2.0, 4.5 m) grow faster than linearly in time; in fact distance is roughly proportional to time squared, which is the signature of constant acceleration. A constant-speed cart would show equal distance increments each second.

Question 11Physics: measurements, energy and circuits

A passenger standing in a bus lurches forward when the bus brakes suddenly. Which property of matter explains this?

  1. Gravity pulls the passenger forward
  2. The bus pulls the passenger with a string
  3. Friction pushes the passenger forward
  4. Inertia keeps the passenger moving at the old speed Correct answer.

Explanation

An object keeps its state of motion unless a force acts on it (inertia, 慣性). When the bus slows, the passenger's body tends to keep moving at the original speed, so they lurch forward.

Question 12Physics: measurements, energy and circuits

An object of mass 2 kg moves at 3 m/s. What is its kinetic energy (運動エネルギー)?

  1. 3 J
  2. 18 J
  3. 6 J
  4. 9 J Correct answer.

Explanation

Kinetic energy equals one half times mass times speed squared (E = ½mv²). That gives 0.5 × 2 × 3² = 0.5 × 2 × 9 = 9 J.

Question 13Physics: measurements, energy and circuits

A 0.5 kg ball is lifted to a height of 4 m. Taking g ≈ 10 m/s², how much gravitational potential energy (位置エネルギー) does it gain?

  1. 20 J Correct answer.
  2. 0.125 J
  3. 1.25 J
  4. 2 J

Explanation

Potential energy equals mass times g times height (E = mgh). That gives 0.5 × 10 × 4 = 20 J.

Question 14Physics: measurements, energy and circuits

As a ball falls freely (without air resistance), how do its kinetic and potential energies change?

  1. Both energies decrease
  2. Potential decreases and kinetic increases; the total stays constant Correct answer.
  3. Both energies increase
  4. Potential increases and kinetic decreases; the total stays constant

Explanation

As the ball falls, height drops so potential energy decreases, while speed rises so kinetic energy increases. With no air resistance the total mechanical energy is conserved.

Question 15Physics: measurements, energy and circuits

An object is placed beyond twice the focal length of a convex lens (凸レンズ). What kind of image is formed on the other side?

  1. No image is formed
  2. A virtual, upright, enlarged image
  3. A real, inverted, enlarged image
  4. A real, inverted, reduced image Correct answer.

Explanation

When the object is beyond 2f from a convex lens, the lens forms a real, inverted, reduced image on the opposite side between f and 2f. This is the principle of a camera.

Question 16Physics: measurements, energy and circuits

A light ray hits a flat mirror at 30° from the normal (法線). What is the angle of reflection?

  1. 30° Correct answer.
  2. 60°
  3. 0°
  4. 90°

Explanation

The law of reflection states that the angle of incidence equals the angle of reflection, both measured from the normal. A 30° incidence angle gives a 30° reflection angle.

Question 17Physics: measurements, energy and circuits

Why can sound not travel through a vacuum (真空)?

  1. Vacuum absorbs sound completely
  2. Sound is too fast in a vacuum
  3. Sound becomes light in a vacuum
  4. Sound needs a medium to carry the vibration Correct answer.

Explanation

Sound is a mechanical wave that propagates as particles of a medium vibrate and pass the vibration on. Without any medium (a vacuum) there is nothing to vibrate, so sound cannot travel.

Question 18Physics: measurements, energy and circuits

What is the shape of the magnetic field (磁界) around a straight current-carrying wire?

  1. Straight lines parallel to the wire
  2. Concentric circles around the wire Correct answer.
  3. A single straight line along the wire
  4. Random with no pattern

Explanation

A current through a straight wire produces a magnetic field that forms concentric circles around the wire, as shown by iron-filings and right-hand-rule experiments.

Question 19Physics: measurements, energy and circuits

Which change makes an electromagnet (電磁石) stronger?

  1. Using a non-metallic core
  2. Removing the iron core
  3. Decreasing the current
  4. Increasing the number of coil turns Correct answer.

Explanation

An electromagnet's strength grows with both the current and the number of coil turns. Adding more turns of wire around the core increases the magnetic field.

Question 20Physics: measurements, energy and circuits

An object floats in water. Which statement about the buoyant force (浮力) is correct?

  1. Buoyant force equals the object's mass only
  2. Buoyant force is always zero for floating objects
  3. Buoyant force equals the weight of the fluid displaced by the object Correct answer.
  4. Buoyant force points downward

Explanation

Archimedes' principle states that the buoyant force on a submerged or floating object equals the weight of the fluid it displaces. For a floating object this exactly balances the object's weight.

Question 21Physics: measurements, energy and circuits

A block has mass 120 g and volume 30 cm³. What is its density (密度)?

  1. 4 g/cm³ Correct answer.
  2. 150 g/cm³
  3. 0.25 g/cm³
  4. 3,600 g/cm³

Explanation

Density equals mass divided by volume. One hundred twenty grams divided by 30 cm³ equals 4 g/cm³.

Question 22Physics: measurements, energy and circuits

How does heat mainly travel through a metal spoon when one end is placed in hot soup?

  1. By convection currents in the metal
  2. By conduction, as vibrating particles pass energy to neighbours Correct answer.
  3. By radiation through the air
  4. By evaporation of the soup

Explanation

In solids such as metal, heat travels mainly by conduction: particles vibrate more vigorously and pass kinetic energy to neighbouring particles. Convection occurs in fluids, not solids.

Question 23Physics: measurements, energy and circuits

Two pendulums (振り子) have the same length but different bob masses. Which statement is correct (assuming small swings)?

  1. The lighter pendulum has a longer period
  2. The period depends on the amplitude
  3. Both pendulums have the same period Correct answer.
  4. The heavier pendulum has a longer period

Explanation

For small swings the period of a simple pendulum depends only on the length and on g, not on the bob mass or amplitude. Equal length means equal period.

Question 24Physics: measurements, energy and circuits

A 6 V battery is connected to two resistors of 2 Ω and 4 Ω in series. What is the voltage across the 2 Ω resistor?

  1. 2 V Correct answer.
  2. 6 V
  3. 4 V
  4. 1 V

Explanation

In series the total resistance is 6 Ω, so the current is I = V/R = 6/6 = 1 A. The voltage across the 2 Ω resistor is V = IR = 1 × 2 = 2 V.

Question 25Chemistry: particles, reactions and mass

In the particle model (粒子モデル), why does a solid keep its own shape while a liquid takes the shape of its container?

  1. Solid particles are fixed in position by strong attractive forces, liquid particles can move past one another Correct answer.
  2. Liquid particles vibrate more slowly than solid particles
  3. Solid particles are not made of atoms
  4. Solid particles are larger than liquid particles

Explanation

In a solid the particles are held in fixed positions by strong inter-particle forces, so the solid holds its shape. In a liquid the forces are weaker and particles can slide past one another, so the liquid takes the container's shape.

Question 26Chemistry: particles, reactions and mass

During melting (融解) of ice at 0 °C, what happens to the temperature while the ice is turning into water?

  1. The temperature keeps rising steadily
  2. The temperature drops below 0 °C
  3. The temperature jumps to 100 °C
  4. The temperature stays at 0 °C until all the ice has melted Correct answer.

Explanation

During a state change the absorbed heat goes into breaking the bonds between particles rather than raising temperature, so the temperature stays constant at the melting point until the change is complete.

Question 27Chemistry: particles, reactions and mass

Which pair correctly gives a way to generate hydrogen (水素) and the chemical test used to identify it?

  1. Decompose water with electricity; test gives milky limewater
  2. React zinc with hydrochloric acid; test with a glowing splint (火のついた線香) that burns more brightly
  3. Heat copper(II) oxide; test with limewater turns milky
  4. React zinc with hydrochloric acid; test with a lit splint gives a 'pop' sound Correct answer.

Explanation

Hydrogen is generated by reacting a metal such as zinc with dilute hydrochloric acid. It is identified by the 'pop' sound (爆鳴音) when a lit splint is brought to the mouth of the test tube, because hydrogen burns explosively with oxygen.

Question 28Chemistry: particles, reactions and mass

Oxygen (酸素) is generated in the laboratory by decomposing hydrogen peroxide with manganese dioxide. What role does manganese dioxide play?

  1. It is the product of the reaction
  2. It is a catalyst (触媒) that speeds the reaction without being consumed Correct answer.
  3. It reacts and is used up
  4. It cools the reaction down

Explanation

Manganese dioxide acts as a catalyst: it speeds up the decomposition of hydrogen peroxide into water and oxygen but is not consumed. The same catalyst can be recovered at the end.

Question 29Chemistry: particles, reactions and mass

Which gas turns limewater (石灰水) milky, and what does this confirm?

  1. Carbon dioxide; the milky colour is calcium carbonate formed Correct answer.
  2. Hydrogen; confirms combustion
  3. Oxygen; confirms respiration
  4. Nitrogen; confirms the air is dry

Explanation

Carbon dioxide (二酸化炭素) turns limewater milky because it reacts with calcium hydroxide to form insoluble calcium carbonate, which appears as a white suspension. This is the standard test for carbon dioxide.

Question 30Chemistry: particles, reactions and mass

A solubility curve (溶解度曲線) shows that 40 g of a salt dissolves in 100 g of water at 60 °C and 20 g at 20 °C. If a saturated solution is cooled from 60 °C to 20 °C, how much salt crystallises out?

  1. 60 g
  2. 10 g
  3. 40 g
  4. 20 g Correct answer.

Explanation

At 60 °C the 100 g of water holds 40 g; at 20 °C it holds only 20 g. The difference, 40 − 20 = 20 g, can no longer stay dissolved and crystallises out.

Question 31Chemistry: particles, reactions and mass

A solution contains 15 g of salt dissolved in 85 g of water. What is the mass-percent concentration (質量パーセント濃度)?

  1. 15% Correct answer.
  2. 85%
  3. 5.9%
  4. 17.6%

Explanation

Mass-percent concentration equals the mass of solute divided by the total mass of solution, times 100. The solution mass is 15 + 85 = 100 g, so the concentration is (15/100) × 100 = 15%.

Question 32Chemistry: particles, reactions and mass

In a closed container, 12 g of magnesium reacts with oxygen to form magnesium oxide (MgO) of mass 20 g. What mass of oxygen combined with the magnesium?

  1. 32 g
  2. 8 g Correct answer.
  3. 20 g
  4. 12 g

Explanation

By the law of conservation of mass (質量保存の法則), the total mass of the product equals the total mass of the reactants. The oxygen mass is 20 − 12 = 8 g.

Question 33Chemistry: particles, reactions and mass

When copper(II) hydroxide is heated, it decomposes into copper(II) oxide and water. What is this type of reaction called?

  1. Neutralisation
  2. Combustion
  3. Polymerisation
  4. Thermal decomposition (熱分解) Correct answer.

Explanation

A reaction in which a single compound breaks down into two or more substances by heat is called thermal decomposition. Copper(II) hydroxide, which is blue, breaks into black copper(II) oxide and water on heating.

Question 34Chemistry: particles, reactions and mass

Which three conditions are needed for combustion (燃焼) to occur?

  1. Carbon dioxide, fuel and water
  2. Oxygen, water and a low temperature
  3. Nitrogen, fuel and a match
  4. Oxygen, fuel and a temperature at or above the ignition point Correct answer.

Explanation

Combustion requires three things together: a combustible fuel, oxygen (usually from the air), and a temperature at or above the ignition point (着火点). Removing any one of the three extinguishes the fire.

Question 35Chemistry: particles, reactions and mass

Which pH value indicates a strongly acidic solution?

  1. pH 1 Correct answer.
  2. pH 9
  3. pH 14
  4. pH 7

Explanation

On the pH scale, values below 7 are acidic, 7 is neutral, and values above 7 are basic. The lower the pH, the more strongly acidic the solution, so pH 1 is strongly acidic.

Question 36Chemistry: particles, reactions and mass

Hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH). What kind of reaction is this, and what are the products?

  1. Combustion; carbon dioxide and water
  2. Polymerisation; polyethylene
  3. Neutralisation (中和); sodium chloride and water Correct answer.
  4. Decomposition; hydrogen and oxygen

Explanation

An acid plus a base gives a salt and water; this is neutralisation (中和反応). HCl + NaOH produces NaCl (sodium chloride, common salt) and water (H₂O).

Question 37Chemistry: particles, reactions and mass

A copper rod is dipped in silver nitrate solution. Silver metal coats the rod and the solution turns blue. What does this show about the metals' reactivity?

  1. No reaction occurred
  2. Silver is more reactive than copper
  3. Both metals have equal reactivity
  4. Copper is more reactive than silver Correct answer.

Explanation

A more reactive metal displaces a less reactive metal from its compound in solution. Copper pushes silver out of silver nitrate, so copper is more reactive than silver.

Question 38Chemistry: particles, reactions and mass

In the electrolysis of water (水の電気分解), what is the volume ratio of hydrogen to oxygen collected at the electrodes?

  1. 1:2
  2. 1:1
  3. 2:1 Correct answer.
  4. 4:1

Explanation

Water is H₂O, so electrolysis produces twice as many hydrogen molecules as oxygen molecules, and at the same temperature and pressure the gas volume ratio is 2:1 (hydrogen:oxygen).

Question 39Chemistry: particles, reactions and mass

When copper is heated in air, it gains mass and becomes black. What is the reaction, and what type is it?

  1. Copper melts; a physical change
  2. Copper decomposes; thermal decomposition
  3. Copper combines with oxygen to form copper(II) oxide; oxidation (酸化) Correct answer.
  4. Copper loses oxygen; reduction

Explanation

Heated copper reacts with oxygen in the air to form black copper(II) oxide. A reaction in which a substance combines with oxygen is called oxidation (酸化), and the mass increase equals the oxygen that has joined.

Question 40Chemistry: particles, reactions and mass

When hydrogen is passed over hot copper(II) oxide, the black solid turns red and water is formed. What has happened to the copper(II) oxide?

  1. It has decomposed thermally
  2. It has been reduced (還元) to copper Correct answer.
  3. It has been neutralised
  4. It has been oxidised

Explanation

Hydrogen takes oxygen away from copper(II) oxide, leaving red metallic copper and forming water. A reaction in which a substance loses oxygen is called reduction (還元), and the hydrogen is the reducing agent.

Question 41Chemistry: particles, reactions and mass

Which of the following is the correct order of metal reactivity (反応性) from most to least reactive?

  1. Fe > K > Na > Cu > Ag
  2. K > Na > Fe > Cu > Ag Correct answer.
  3. Ag > Cu > Fe > Na > K
  4. Na > K > Fe > Ag > Cu

Explanation

The reactivity series places the alkali metals potassium and sodium at the top, then less reactive metals like iron, then copper, and finally very unreactive silver at the bottom. So K > Na > Fe > Cu > Ag.

Question 42Chemistry: particles, reactions and mass

Which statement correctly distinguishes atoms (原子) and molecules (分子)?

  1. Atoms and molecules are identical
  2. An atom is the smallest unit of an element; a molecule is two or more atoms joined chemically Correct answer.
  3. Molecules are smaller than atoms
  4. Atoms only exist inside molecules

Explanation

An atom is the smallest particle of an element that retains its chemical identity. A molecule is a group of two or more atoms held together by chemical bonds, such as O₂ or H₂O.

Question 43Chemistry: particles, reactions and mass

Which substance is an electrolyte (電解質) that conducts electricity when dissolved in water?

  1. Salt (NaCl) solution Correct answer.
  2. Alcohol solution
  3. Pure water
  4. Sugar solution

Explanation

An electrolyte is a substance that breaks into ions in water and so conducts electricity. Sodium chloride dissociates into Na⁺ and Cl⁻ ions, making its solution conduct; sugar and alcohol dissolve as molecules and do not form ions.

Question 44Chemistry: particles, reactions and mass

An unknown solid is added to water. The mixture is then filtered, and a clear filtrate is obtained. Which term best describes the filtrate?

  1. A suspension
  2. A precipitate
  3. An alloy
  4. A solution (水溶液) Correct answer.

Explanation

Filtration removes undissolved solids. The clear liquid that passes through the filter paper is the solution (水溶液): the dissolved particles of solute plus the solvent (water).

Question 45Chemistry: particles, reactions and mass

A blue liquid gives off a gas when an electric current is passed through it, and the liquid gradually turns a different colour. Which observation best supports that a chemical change has occurred?

  1. The liquid simply gets warmer
  2. The liquid level drops slightly
  3. A new substance with different colour and properties is formed Correct answer.
  4. Bubbles appear for an instant without any new substance

Explanation

A chemical change produces one or more new substances with properties (such as colour) different from the starting material. The lasting colour change and gas evolution show that new substances have formed, not just a temporary physical change.

Question 46Chemistry: particles, reactions and mass

Which ion (イオン) is produced by an acid in water?

  1. Sodium ion (Na⁺)
  2. Hydroxide ion (OH⁻)
  3. Chloride ion (Cl⁻)
  4. Hydrogen ion (H⁺) Correct answer.

Explanation

Acids are substances that release hydrogen ions (H⁺) when dissolved in water; this is what gives acidic solutions their low pH. Bases, by contrast, release hydroxide ions (OH⁻).

Question 47Chemistry: particles, reactions and mass

In an experiment, 10 cm³ of a hydrochloric acid solution is exactly neutralised by 8 cm³ of a sodium hydroxide solution. What volume of the same sodium hydroxide solution exactly neutralises 25 cm³ of the same hydrochloric acid?

  1. 23 cm³
  2. 20 cm³ Correct answer.
  3. 16 cm³
  4. 31.25 cm³

Explanation

The same acid and alkali always neutralise each other in a fixed volume ratio. Here that ratio is 10 : 8, which simplifies to 5 : 4. Scaling up to 25 cm³ of acid gives 25 × 4/5 = 20 cm³ of sodium hydroxide.

Question 48Chemistry: particles, reactions and mass

Which property is typical of a base (塩基), not of an acid?

  1. Turns blue litmus red
  2. Reacts with metals to give hydrogen
  3. Turns red litmus blue Correct answer.
  4. Has a sour taste

Explanation

Bases turn red litmus paper blue, the characteristic colour change for an alkaline solution. Acids do the opposite: they turn blue litmus red, and they react with active metals to release hydrogen.

Question 49Chemistry: particles, reactions and mass

When a sealed, flexible balloon of gas is cooled, the balloon shrinks. Which particle-model explanation is correct?

  1. The particles stop moving entirely
  2. The particles lose kinetic energy and the gas pressure drops so the outside air squeezes the balloon smaller Correct answer.
  3. Some particles disappear when cooled
  4. The particles themselves shrink in size

Explanation

Cooling reduces the average kinetic energy of the gas particles, so they hit the balloon walls less hard and less often and the pressure falls. The outside air pressure then squeezes the balloon smaller until the pressures balance.

Question 50Biology: cells, inheritance and evidence

Which organelle (細胞小器官) is the site of cellular respiration (細胞呼吸) and is called the 'powerhouse of the cell'?

  1. Cell membrane
  2. Mitochondria (ミトコンドリア) Correct answer.
  3. Chloroplast
  4. Nucleus

Explanation

Mitochondria carry out respiration, releasing energy from glucose for the cell's activities, which is why they are called the powerhouse. Chloroplasts carry out photosynthesis instead, and the nucleus stores genetic information.