Nature of Science
Why is scientific knowledge considered to be dependable?
It can change if new evidence comes about.
Which of the following is an element? Salt, Oxygen, Vinegar, Water
Oxygen
What does gravity depend on?
The gravitational force between two objects depends on the masses of the objects.
Jessica wanted to change a liquid into a solid. What must she do to bring about this change in state?
Increase the energy of the liquid so that its particles move faster.
Describe the most likely evidence of a chemical change?
A substance gives off heat and light.
Hanna is at the beach and witnesses high tides and low tides. What causes tides?
the pull of the moon’s gravity
Describes what happens to a scientific theory when new information is discovered?
A scientific theory is changed when new evidence is discovered.
Describes the structure of atoms?
Atoms contain electrons found outside the nucleus, which are attracted to the positively charged nucleus.
How can two objects with the same mass have a different density?
The two objects have a different volume.
Describes the direction of heat flow in order to change a liquid into a gas?
Heat must be added to the liquid.
Describe a chemical change.
A chemical change produces new substances with different properties than the original substances.
What is a direct result of Earth’s tilted axis?
seasons
In a scientific discussion, what is the most rigorous support of a claim?
experimental evidence
What is the atomic number of an element based upon?
number of protons in its nucleus.
Two objects have the same mass, but one object occupies a smaller volume than the other. Describe a statement about the objects must be true?
The two objects have different densities.
Why is the state of matter considered a physical property even though a substance may change between a solid, liquid, and gas?
The chemical nature of the substance does not change.
Describes how a chemical change is different from a physical change?
Only a chemical change produces a new substance.
Halley's comet orbits the Sun because
the force of gravity between the comet and the Sun influences the comet’s motion.
A group of scientists has made a new discovery. What would have to happen before their discovery can become a scientific theory?
Many other scientists would have to verify the validity of their findings in order for their discovery to become a theory.
How is an element different from a compound?
an element is made of a single type of atom, and a compound is made of two or more atom types.
A student is given a mixture of small pieces of iron, sand, water, and salt. What physical property could be used to best separate the iron from the other ingredients?
magnetism
What best describes a gas and its particles?
A gas assumes the shape and volume of its container; gas particles can move freely.
In a neutralization reaction, an acid and a base neutralize each other. Water is one of two products What is the other product?
Salt
The Sun and the Moon influence Earth's tides, but the Moon's influence is greater than the Sun's. Why is this the case?
The Sun has more mass than the Moon. But the Moon is much closer to Earth than the Sun, so its gravitational force on Earth is greater.
What should a scientist do if a hypothesis is NOT supported by data?
Carry out further investigations.
Describes a scientific hypothesis?
a testable scientific explanation based on observation
All objects are made up of matter. If you measure the amount of matter in an object, what have you measured?
its mass
What happens when ice turns into liquid water?
Energy is absorbed by the molecules.
How does the temperature in a refrigerator influence the chemical changes in the food?
The rate of chemical change decreases.
Which of the following does NOT happen because of gravitational pull? Tides, Season, Moon phases, Day and Night
Day and Night
Why are replications of an experiment necessary?
to ensure that the experiment is reproducible
Which elements would also be a member of this group, and why?
Any element located vertically in the periodic table, they share the same number of valence electrons
Mario performed an experiment to investigate how certain substances dissolve in water. What physical property of the substances did Mario investigate? density, solubility, melting point, thermal conductivity
solubility
Adding heat to a system may result in a change in temperature and possibly a change of state. What could result from heat being transferred to a substance?
The temperature of the substance increases. Liquid to gas or solid to liquid
Which process involves only a physical change? a candle burning, an ice cube melting, an egg cooking, a nail rusting
an ice cube melting
Distances among planets and stars are too large in everyday distance units. Which units would be used when measuring the distances between planets?
astronomical unit
Which method is the best way to make the results of an experiment more valid?
by repeating the number of measurements
A chemist determines that the atom she is studying has eight negatively charged particles outside the nucleus. What does this indicate about the atom?
It contains eight electrons.
An object moves from one location to another location that has different gravity. Why does the object's mass stay constant, while its weight changes?
Mass does not change because the amount of matter stays the same.
Thomas performed an experiment to measure the temperature of water as he heated it on a hotplate. What physical properties of water did Thomas measure?
melting point and boiling point
One of the students accidentally drops the box when removing it from the balance, and the crystal breaks into 20 pieces. What happens to the mass of the box and crystal after the crystal is broken?
The mass remains the same.
Which of the following objects is farthest from Earth, Andromeda Galaxy, Neptune, North Star,
The Sun
Andromeda Galaxy