Question 1
During a physical change like melting, what quantity stays the same before and after?
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Mass
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Temperature
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State of matter
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Chemical composition
Question 2
Compared to gases, how are the particles in a solid arranged?
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Packed closely together and vibrate in place
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Farther apart and move randomly
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In straight lines at high speed
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Completely stationary
Question 3
What does Brownian motion show about particles in a gas?
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They move randomly and collide with moving dust particles
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They stay still until heated
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They spin like electrons
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They evaporate instantly
Question 4
Which process is an example of diffusion?
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Perfume spreading through air
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Water boiling in a kettle
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Magnet sticking to a fridge
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A car accelerating on a road
Question 5
Which equation defines density \(\rho\)?
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\(\rho = \frac{m}{V}\)
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\(\rho = mV\)
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\(\rho = \frac{V}{m}\)
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\(\rho = m + V\)
Question 6
If a block has mass \(3\,\mathrm{kg}\) and volume \(0.50\,\mathrm{m}^3\), what is its density?
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\(6\,\mathrm{kg/m^3}\)
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\(1.5\,\mathrm{kg/m^3}\)
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\(2\,\mathrm{kg/m^3}\)
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\(10\,\mathrm{kg/m^3}\)
Question 7
Inside a material, what store holds the energy of particles' motion and positions?
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Internal energy
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Chemical potential
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Kinetic electricity
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Pressure
Question 8
Which equation gives the energy for a change of state?
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\(E = mL\)
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\(E = mc\Delta \theta\)
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\(E = mgh\)
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\(E = P t\)
Question 9
What happens to the internal energy of ice as it melts into water?
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It increases while the temperature stays constant
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It drops to zero
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It stays constant and the temperature falls
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It turns into mass
Question 10
What does specific heat capacity measure?
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Energy needed to raise \(1\,\mathrm{kg}\) of a substance by \(1\,\mathrm{°C}\)
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Mass lost during heating
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Temperature change per second
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Number of particles
Question 11
Which change conserves both mass and chemical composition?
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Evaporation of water
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Burning paper
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Iron rusting
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Baking a cake
Question 12
When water condenses, what happens to the energy stored by the particles?
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It decreases and is transferred to the surroundings
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It increases
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It stays trapped inside the droplets
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It turns into magnetic energy
Question 13
Why does diffusion happen faster at higher temperatures?
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Particles move faster and collide more often
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The medium becomes solid
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Gravity becomes stronger
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Materials gain extra mass
Question 14
When a solid melts, what happens to the spacing between particles?
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It increases
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It stays the same
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It decreases
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Particles disappear
Question 15
Which state has particles sliding past each other while still touching?
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Liquid
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Solid
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Gas
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Plasma
Question 16
How does temperature affect internal energy of a fixed mass?
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Higher temperature means more internal energy
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Temperature has no effect
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Lower temperature means more energy
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Internal energy becomes zero always
Question 17
Which process is reversible without changing substances?
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Freezing and melting
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Burning
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Rusting
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Baking
Question 18
What happens to density when a gas is compressed to a smaller volume?
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It increases
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It decreases
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It stays the same
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It becomes negative
Question 19
Which term describes materials that keep their mass during heating?
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Conservation of mass
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Mass creation
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Mass elimination
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Mass explosion
Question 20
Why is the particle model useful?
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It explains changes of state and density differences
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It predicts asteroids
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It calculates energy bills
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It shows chemical reactions only
Question 21
A metal block has mass \(2.4\,\mathrm{kg}\) and volume \(0.80\,\mathrm{m}^3\). What is its density?
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\(3\,\mathrm{kg/m^3}\)
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\(0.30\,\mathrm{kg/m^3}\)
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\(3000\,\mathrm{kg/m^3}\)
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\(2.4\,\mathrm{kg/m^3}\)