PHYSCI ETA

Which of the following discoveries by Galileo most strongly contradicted the Ptolemaic model?

• The discovery of neutron stars

• The identification of comets beyond the atmosphere

• The moons of Jupiter orbiting around Jupiter instead of Earth

• The presence of Saturn’s rings
  Correct Answer: The moons of Jupiter orbiting around Jupiter instead of Earth

According to Kepler’s Third Law, planets farther from the Sun:

• Have longer orbital periods

• Travel faster

• Rotate faster on their axis

• Experience stronger gravitational forces
  Correct Answer: Have longer orbital periods

In free-fall motion near Earth’s surface, objects experience:

• Constant acceleration of approximately 9.8 m/s²

• Decreasing acceleration as they gain speed

• Zero acceleration due to weightlessness

• Increased air resistance leading to faster speeds
  Correct Answer: Constant acceleration of approximately 9.8 m/s²

What happens when a star attempts to fuse elements heavier than iron?

• It releases energy and forms new isotopes

• It continues nuclear fusion at an accelerated rate

• It collapses and triggers a supernova

• It undergoes slow expansion into a supergiant
  Correct Answer: It collapses and triggers a supernova

What evidence did Eratosthenes use to determine that the Earth was spherical?

• The way objects fall towards the ground

• The motion of the planets relative to the stars

• The appearance of the Moon during an eclipse

• The difference in shadow angles at different locations
  Correct Answer: The difference in shadow angles at different locations

According to Plato, what was the problem of “Saving the Appearances” in Greek astronomy?

• Finding evidence that stars move independently of planets

• Explaining planetary motion while preserving the idea of perfect circular orbits

• Justifying why the Sun appears larger at noon

• Proving that the Earth was the center of the universe
  Correct Answer: Explaining planetary motion while preserving the idea of perfect circular orbits

If you throw a ball straight upward, at its highest point, the ball’s velocity is:

• Zero

• Increasing

• Maximum

• Equal to the initial velocity
  Correct Answer: Zero

When a cyclist applies brakes, the bicycle slows down due to:

• Centripetal force acting outward

• Gravity pulling downward

• Friction between the tires and the road

• Newton’s First Law causing acceleration
  Correct Answer: Friction between the tires and the road

A catalyst works by:

• Absorbing heat

• Lowering activation energy

• Increasing reaction temperature

• Raising energy requirements
  Correct Answer: Lowering activation energy

A chemical equation must be balanced to:

• Adjust the reaction rate

• Keep the number of molecules equal

• Ensure the conservation of mass

• Prevent energy loss
  Correct Answer: Ensure the conservation of mass

A car traveling at 20 m/s has a kinetic energy of 4000 J. If its speed doubles, what happens to its kinetic energy?

• It quadruples

• It doubles

• It decreases

• It remains the same
  Correct Answer: It quadruples
  (Remember: Kinetic energy ∝ speed².)

What happens when two vehicles of different sizes crash into each other and stay stuck together after the collision?

• They bounce off each other completely

• They separate but still keep some of their shape

• They never actually collide

• They stay joined together after impact
  Correct Answer: They stay joined together after impact
  (This is an example of an inelastic collision.)

Galileo’s observation that weakened the geocentric model was:

• Venus’ phases similar to the Moon

• The Moon’s craters

• The motion of comets

• The Sun’s dark spots
  Correct Answer: Venus’ phases similar to the Moon
  (This observation showed that not everything orbited the Earth.)

JJ Thomson’s work contributed to atomic theory by:

• Establishing quantum orbitals

• Proving atoms are indivisible

• Identifying the electron

• Discovering the neutron
  Correct Answer: Identifying the electron

How did Ptolemy attempt to explain retrograde motion in the geocentric model?

• By suggesting that planets were closer to Earth than stars

• By introducing epicycles

• By arguing that gravity altered planetary motion

• By claiming that planets moved randomly
  Correct Answer: By introducing epicycles

The atomic number of an element is determined by its number of:

• Protons

• Neutrons

• Isotopes

• Electrons
  Correct Answer: Protons

Why can nuclear fusion not occur naturally beyond iron?

• The process generates too much pressure

• Iron nuclei are too unstable to bond

• Protons decay into neutrons before fusion occurs

• Fusion past iron requires more energy than it releases
  Correct Answer: Fusion past iron requires more energy than it releases

CO₂ is classified as:

• Ionic

• Polar

• Nonpolar

• Bipolar
  Correct Answer: Nonpolar
  (Despite polar C=O bonds, the linear geometry causes cancellation.)

What happens when intermolecular forces weaken?

• Gases become more compressed

• Liquids evaporate more quickly

• Solids gain higher density

• Water becomes less soluble
  Correct Answer: Liquids evaporate more quickly

Stronger intermolecular forces lead to:

• Weaker molecular attraction

• Lower boiling points

• Faster reaction rates

• Higher boiling points
  Correct Answer: Higher boiling points

In projectile motion, the horizontal and vertical components of motion:

• Change randomly

• Are independent of each other

• Depend on the shape of the projectile

• Are always equal
  Correct Answer: Are independent of each other

Which scientific principle best explains why satellites remain in orbit?

• The principle of conservation of momentum

• Newton’s First Law – objects in motion stay in motion unless acted upon by an external force

• Kepler’s Third Law – orbital period is related to distance from the center

• Newton’s Third Law – for every action, there is an equal and opposite reaction
  Correct Answer: Newton’s First Law – objects in motion stay in motion unless acted upon by an external force
  (This reflects the concept of inertia.)

Changing which subatomic particle will transform one element into another?

• Atomic Mass

• Protons

• Electrons

• Neutrons
  Correct Answer: Protons
  (The number of protons defines the element.)

If an atom has 15 protons and a mass of 31, how many neutrons does it have?

• 15

• 31

• 46

• 16
  Correct Answer: 16
  (31 – 15 = 16)

London dispersion forces occur when:

• Hydrogen bonds form

• Water molecules align

• Temporary dipoles arise in nonpolar molecules

• Ions form in a solution
  Correct Answer: Temporary dipoles arise in nonpolar molecules

If an astronaut drops a hammer and a feather on the Moon, what will happen?

• Both hit the ground at the same time due to the absence of air resistance

• The feather floats in the air

• The hammer falls faster, but the feather takes longer

• The hammer falls first due to its mass
  Correct Answer: Both hit the ground at the same time due to the absence of air resistance

What determines molecular polarity?

• The boiling point of the compound

• The shape and electron distribution

• The phase of the molecule

• The number of atoms in the molecule
  Correct Answer: The shape and electron distribution

Which of the following statements best describes momentum?

• It can exist without motion

• It depends only on the object’s speed

• It is the product of an object’s mass and velocity

• It is the same as kinetic energy
  Correct Answer: It is the product of an object’s mass and velocity

What observational evidence supports the Big Bang theory’s prediction of light element formation?

• The abundance of hydrogen and helium

• Neutron

• The detection of neutrinos in space

• The expansion of the universe
  Correct Answer: The abundance of hydrogen and helium

According to Newton’s Second Law of Motion, if the net force applied to an object is doubled while its mass remains constant, what happens to its acceleration?

• It doubles

• It remains the same

• It is reduced by half

• It increases fourfold
  Correct Answer: It doubles

A rocket moves forward in space by:

• Using magnetism to repel Earth’s gravity

• Pushing against the vacuum of space

• Absorbing solar radiation and converting it into thrust

• Expelling gas backward, creating an equal and opposite reaction
  Correct Answer: Expelling gas backward, creating an equal and opposite reaction

What experiment led to the discovery of the atomic nucleus?

• The discovery of X-rays

• Millikan’s oil drop experiment

• Rutherford’s gold foil experiment

• JJ Thomson’s cathode ray experiment
  Correct Answer: Rutherford’s gold foil experiment

Why do astronauts appear weightless in the International Space Station?

• There is no gravity in space

• They are in free fall, constantly falling toward Earth while moving forward

• Their mass is reduced in low gravity

• The space station counteracts Earth’s gravity
  Correct Answer: They are in free fall, constantly falling toward Earth while moving forward

Nuclear fusion occurs in stars because:

• Neutron decay produces large energy bursts

• Atomic mass decreases, causing nuclei to split

• High temperatures and pressures force nuclei to combine

• Electrons orbit around protons and create heavier elements
  Correct Answer: High temperatures and pressures force nuclei to combine

Which molecule exhibits the strongest intermolecular forces?

• CO₂

• CH₄

• H₂O

• O₂
  Correct Answer: H₂O
  (Hydrogen bonding in water is very strong.)

The limiting reactant in a chemical reaction:

• Can always be adjusted

• Controls reaction speed

• Determines the maximum product yield

• Remains unreacted
  Correct Answer: Determines the maximum product yield

An example of a chemical change is:

• Melting ice

• Cutting paper

• Rust forming on iron

• Dissolving salt in water
  Correct Answer: Rust forming on iron
  (Rusting involves a chemical reaction.)

Raising temperature in a reaction generally:

• Increases collision frequency and reaction rate

• Decreases molecular motion

• Prevents activation energy from being reached

• Lowers kinetic energy
  Correct Answer: Increases collision frequency and reaction rate

The process responsible for the formation of the first elements in the universe is called:

• Electron capture

• Stellar nuclear fusion

• Primordial nucleosynthesis

• Beta decay
  Correct Answer: Primordial nucleosynthesis

The total mechanical energy of a system is conserved when:

• Friction and external forces are present

• The system is at rest

• Only conservative forces (such as gravity) are acting

• Energy is lost as heat
  Correct Answer: Only conservative forces (such as gravity) are acting

What happens to the gravitational force between two objects if their masses remain the same but the distance between them is tripled?

• It doubles

• It triples

• It remains unchanged

• It becomes 1/9 of the original force
  Correct Answer: It becomes 1/9 of the original force
  (Gravitational force ∝ 1/d².)

The majority of elements heavier than iron originate from:

• The fusion reactions in low-mass stars

• The Sun’s corona

• Supernova explosions

• Gas clouds in the Milky Way
  Correct Answer: Supernova explosions

A reaction releases more energy than it absorbs. It is classified as:

• Exothermic

• Spontaneous

• Endothermic

• Equilibrium
  Correct Answer: Exothermic

Which of Kepler’s Laws explains why planets travel faster when they are closer to the Sun?

• Kepler’s First Law (Elliptical Orbits)

• Kepler’s Second Law (Law of Equal Areas)

• Kepler’s Third Law (Orbital Periods)

• The Law of Universal Gravitation
  Correct Answer: Kepler’s Second Law (Law of Equal Areas)

The primary reason a car’s crumple zone increases passenger safety during a crash is that it:

• Reduces the car’s weight

• Makes the car bounce backward

• Increases acceleration to counteract impact

• Increases the time over which the impact occurs, reducing force
  Correct Answer: Increases the time over which the impact occurs, reducing force