a) Answer is: The electrical attraction between a <u>proton </u>and an electron is forty powers of ten stronger than their gravitational attraction.
Proton is a subatomic particle with a positive electric charge of +1e elementary charge.
The electron (symbol: e⁻) is a subatomic particle whose electric charge is negative one elementary charge.
Opposite charges (positive and negative) attract one another.
b) Answer is: Lithium, with an <u>atomic mass</u> of 6.94, is the lightest of all the metals and is therefore an obvious candidate for battery use.
The atomic mass is the average mass of element.
The average atomic mass of krypton =
= ω(⁸²Kr) · Ar(⁸²Kr) + ω(⁸³Kr)·Ar(⁸³Kr) + ω(⁸⁴Kr) · Ar(⁸⁴Kr) + ω(⁸⁵Kr)· Ar(⁸⁵Kr).
ω(Kr) is average abundance of isotopes of krypton.
Ar(Kr) is atomic mass of krypton isotope.
Another examples, atomic mass of phosphorus (P) is 30.97 and atomic mass of oxygen (O) is 15.99.
c) Answer is: Protons and neutrons have masses of approximately 1 <u>atomic mass unit
</u> each.
The unified atomic mass unit (amu) is a standard unit of atom mass.
One unified atomic mass unit is approximately the mass of one nucleon (protons or neutrons).
The unified atomic mass unit is equal 1.66·10⁻²⁷ kg.
d) Answer is: Other species can see colors of the spectrum that are invisible to us.
For example, a common butterfly has five times more photoreceptors in their eyes than human.
So butterfly can see ultraviolet and violet spectar of colors (human can not see violet and ultraviolet), they see different wavelength than human.
e) Answer is: Technological advances have taken much of the <u>drudgery</u> out of the assembly line and car plant.
Drudgery is hard monotonous routine work.
At assembly lines and car plant at the beggining of the 20th century, hard work were doing humans, now with technology advances, that work is than by the machines or robots.
f) Answer is: Nitrogen has 7 protons and 7 neutrons in the nucleus, giving it a <u>mass number</u> of 14.
The mass number (A) is sum of the number of protons and the number of neutrons in atom.
n°(N) = 7; number of neutrons in nitrogen atom.
p⁺(N) = 7; number of protons in nitrogen atom.
A = n° + p⁺.
A(N) = 7 + 7.
A(N) = 14; nitrogen mass number is 14.
h) Answer is: The system thus avoids the seemingly <u>interminable</u> delays that bedevil on-line services when they are used to transmit graphics.
Interminable means something continuing for too long and because of that is boring or annoying.
i) Answer is: The nucleus of a deuterium atom contains a proton and a <u>neutron.</u>
Deuterium (₁²H or D) is an isotope of the hydrogen (H).
Deuterium has atomic number 1 (it has one proton) and mass number 2.
p⁺(D) = 1; number of protons in deuterium.
A = n° + p⁺.
A(D) = 2; mass number of deuterium.
n°(D) = 2 -1.
n°(D) = 1; number of neutrons in deuterium.
Isotopes are chemical elements with same atomic number, but different mass number (different number of neutrons).
j) Answer is: Newspapers and television <u>perceive</u> us to slit all the candy open to ensure that it contains no foreign body.
Newspapers and television make us to belief in or about something.
k) Answer is: But barium has an <u>atomic number </u>of 56, barely more than half that of uranium.
Atomic number (Z) is the number of protons (number of protons in neutral atom is the same as number of an electrons), which is characteristic of a chemical element,
Atomic number is unique and defines an element.
Atomic number of uranium (U) is 92 (Z = 92).
l) Answer is: The third <u>isotope</u> of hydrogen, hydrogen-3 or tritium, is highly radioactive and has a very short half-life.
Tritium (₁³H or T) is an isotope of the hydrogen (H).
Tritium has atomic number(Z) 1 and mass number(A) 3.
p⁺(T) = 1; number of protons in the tritium.
A = n° + p⁺.
A(T) = 3; mass number of the tritium.
n°(T) = 3 -1.
n°(T) = 2; number of neutrons in tritium.
Isotopes are chemical elements with same atomic number, but different mass number (different number of neutrons), hydrogen, besides deuterium and tritium, has isotope protium.
