Answer:
a. The letters Na with one dot
Explanation:
An atom can be defined as the smallest unit comprising of matter that forms all chemical elements. Thus, atoms are basically the building blocks of matters and as such determines or defines the structure of a chemical element.
Generally, atoms are typically made up of three distinct particles and these are protons, neutrons and electrons.
In Chemistry, electrons can be defined as subatomic particles that are negatively charged and as such has a magnitude of -1.
Valency can be defined as a measure of the combining power of a chemical element with other atoms to form a molecule or chemical compound.
Valence electrons can be defined as the number of electrons present in the outermost shell of an atom. Thus, valence electrons are used to determine whether an atom or group of elements found in a periodic table can bond with others.
Sodium is a chemical element that is found in group (1) of the periodic table and as such it has 1 electrons in its outermost shell. Also, the chemical symbol for Sodium is Na and it has one (1) valence electron.
A Lewis structure can be defined as a structural representation of an atom or molecule by using a dot to show the position and distribution of electron(s) around the atom or molecule.
Hence, the letters Na with one (1) dot is a correct Lewis structure diagram for Sodium (Na) because it has just one (1) valence electron in outermost shell.
For example, the Lewis structure diagram for Sodium (Na) is •Na.
<span>The complete question includes these choices: a. vitamin B6
b. calcium
c. water
d. protein The correct answer is c. water. Water has a peculiar chemical structure, with special and unique properties that are crucial for chemical reactions (eg good dissolving properties, resistance to pressure and fluidity throughout changes of state).</span>
Explanation:
Red-shift
Emission spectra
Light from a star does not contain all the wavelengths of the electromagnetic spectrum. Elements in the star absorb some of the emitted wavelengths, so dark lines are present when the spectrum is analysed. Different elements produce different patterns of dark lines. The diagram shows part of the emission spectrum of light from the Sun.
A gradient colour spectrum of the sun.
Spectra from distant galaxies
Astronomers can observe light from distant galaxies. When they do this, they see it is different to the light from the Sun. The dark lines in the spectra from distant galaxies show an increase in wavelength. The lines are moved or shifted towards the red end of the spectrum. This effect is called red-shift. The diagram shows part of the emission spectrum of light from a distant galaxy.
A gradient colour spectrum of a distant star.
Red-shift and speed
Astronomers see red-shift in virtually all galaxies. It is a result of the space between the Earth and the galaxies expanding. This expansion stretches out the light waves during their journey to us, shifting them towards the red end of the spectrum. The more red-shifted the light from a galaxy is, the faster the galaxy is moving away from Earth
It is a question to ask nature
