# Conceptual Physics

## Educators

Problem 1

What was all matter composed of according to Aristotle?

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Problem 2

How is Brownian motion observed when the atoms responsible for it are invisible under a microscope?

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Problem 3

Who proposed the idea that matter is composed of atoms? What was Einstein’s contribution to this idea?

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Problem 4

What are the type of speeds at which atoms and molecules in the atmosphere move? Could you say that we are breathing one another?

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Problem 5

Approximately how many atoms are present in a gram of water?

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Problem 6

What limitation does diffraction place on the level of detail seen in an object?

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Problem 7

What technique is used to observe atoms?

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Problem 8

What is the purpose of a model in science?

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Problem 9

What percentage of the volume of an atom does its nucleus occupy?

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Problem 10

What are nucleons with a positive charge called?

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Problem 11

How does the electric charge of a proton compare with the electric charge of an electron?

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Problem 12

Since atoms are mostly empty space, why don’t we fall through a floor we stand on?

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Problem 13

What element has the lightest atoms?

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Problem 14

What is the most abundant element in the known universe?

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Problem 15

How are elements with nuclei heavier than those of hydrogen and helium formed?

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Problem 16

Where did the heaviest elements originate?

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Problem 17

What are the five most common elements in humans?

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Problem 18

What is the basis on which the periodic table of elements is constructed?

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Problem 19

How many shells are represented in the presently known periodic table?

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Problem 20

What kind of attraction pulls electrons close to the atomic nucleus?

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Problem 21

Why is a helium atom smaller than a hydrogen atom?

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Problem 22

How does one isotope differ from another?

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Problem 23

Can mass number be less than atomic number?

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Problem 24

What is a compound? Cite two examples.

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Problem 25

How is a compound different from a mixture?

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Problem 26

How does a molecule differ from an atom?

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Problem 27

Compared with the energy it takes to separate oxygen and hydrogen from water, how much energy is released when they recombine?

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Problem 28

How do matter and antimatter differ?

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Problem 29

What occurs when a particle of matter and a particle of antimatter meet?

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Problem 30

What is the evidence that dark matter exists?

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Problem 31

A candle will burn only if oxygen is present. Will a candle burn twice as long in an inverted liter jar as it will in an inverted half-liter jar? Try it and see.

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Problem 32

Text a letter to Grandma and Grandpa describing how long the atoms that make up their bodies have been around. And how long they will continue to be around.

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Problem 33

Consider the following atoms: A. gold, B. copper, C. car- bon, and D. silver. Consult the periodic table and rank these atoms, from most to least, by their
a. mass.
b. number of electrons.
c. number of protons.

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Problem 34

Rank the numbers of shells in these noble-gas atoms from most to fewest:
a. Argon
c. Helium
d. Neon

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Problem 35

Rank the masses of these molecules from greatest to least.

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Problem 36

What is the difference between an element and an atom? Name the lightest element.

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Problem 37

How many individual atoms is an H2S molecule composed of?

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Problem 38

When a container of gas is heated, would you expect its molecules to speed up, slow down, or be unaffected?

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Problem 39

The average speed of a perfume-vapor molecule at room temperature may be about 300 m/s, but you’ll find the speed at which the scent travels across the room is much less. Why?

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Problem 40

Which of the following is not an element: hydrogen, carbon, oxygen, water?

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Problem 41

Which of the following are pure elements: $\mathrm{H}_{2}, \mathrm{H}_{2} \mathrm{O}, \mathrm{He}$ ,
$\mathrm{Na}, \mathrm{NaCl}, \mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{U}$ ?

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Problem 42

Your friend says that what makes one element distinct from another is the number of electrons around the atomic nucleus. Do you agree wholeheartedly, partially, or not at all? Explain.

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Problem 43

What is the cause of the Brownian motion of dust and other small particles? Why aren’t larger objects, such as baseballs, similarly affected?

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Problem 44

How many atoms are in a molecule of sulfuric acid, $\mathrm{H}_{2} \mathrm{SO}_{4} ?$

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Problem 45

The mass numbers of two isotopes of cobalt are 59 and 60. (a) How many protons and how many neutrons are in each isotope? (b) How many orbiting electrons does an atom of each have when the atoms are electrically neutral?

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Problem 46

A particular atom contains 29 electrons, 34 neutrons, and 29 protons. What is the identity of this element, and what is its atomic number?

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Problem 47

If two protons and two neutrons are removed from the nucleus of an oxygen atom, what nucleus remains?

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Problem 48

What element results if you add a pair of protons to the nucleus of mercury? (See the periodic table.)

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Problem 49

What element results if two protons and two neutrons are ejected from a radium nucleus?

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Problem 50

To become a negative ion, does an atom lose or gain an electron?

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Problem 51

To become a positive ion, does an atom lose or gain an electron?

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Problem 52

You could swallow a capsule of germanium without ill effects. But, if a proton were added to each of the germanium nuclei, you would not want to swallow the capsule. Why? (Consult the periodic table.)

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Problem 53

Helium is an inert gas, which means that it doesn’t readily combine with other elements. What five other elements would you also expect to be inert gases? (See the periodic table.)

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Problem 54

Which of the following elements would you predict to have properties most similar to those of silicon (Si): aluminum (Al), phosphorus (P), or germanium (Ge)? (Consult the periodic table.)

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Problem 55

Which contributes more to an atom’s mass: electrons or protons? Which contributes more to an atom’s size?

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Problem 56

A hydrogen atom and a carbon atom move at the same speed. Which has the greater kinetic energy?

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Problem 57

In a gaseous mixture of hydrogen and oxygen gas, both with the same average kinetic energy, which molecules move faster on average?

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Problem 58

The atoms that make up your body are mostly empty space, and structures such as the chair you’re sitting on are composed of atoms that are also mostly empty space. So why don’t you fall through the chair?

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Problem 59

Make up a multiple-choice question that will test your classmates on the distinction between any two terms in the Summary of Terms list.

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Problem 60

A cat strolls across your backyard. An hour later, a dog with his nose to the ground follows the trail of the cat. Discuss this occurrence from a molecular point of view.

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Problem 61

How is a campfire’s warmth, in fact, stored solar energy?

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Problem 62

Does the increasing population of Earth lead to an increase in its mass?

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Problem 63

Discuss why equal masses of golf balls and Ping-Pong balls don’t contain the same number of balls.

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Problem 64

Discuss why equal masses of carbon atoms and oxygen atoms don’t contain the same number of particles.

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Problem 65

Discuss which contains more atoms: 1 kg of lead or 1 kg of aluminum.

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Problem 66

A carbon atom, with a half-full outer shell of electrons— four in a shell that can hold eight—readily shares its electrons with other atoms and forms a vast number of molecules, many of which are the organic molecules that form the bulk of living matter. Looking at the periodic table, what other element do you think might play a role like carbon in life forms on some other planet?

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Problem 67

In what sense can you truthfully say that you are a part of every person in history? In what sense can you say that you will tangibly contribute to every person on Earth who will follow?

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Problem 68

What are the chances that at least one of the atoms exhaled by your very first breath will be in your next breath?

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Problem 69

Hydrogen and oxygen always react in a 1:8 ratio by mass to form water. Early investigators thought this meant that oxygen was 8 times more massive than hydrogen. What chemical formula did these investigators assume for water?

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