Spiral galaxies have three main components: a bulge, disk, and halo (see right). The bulge is a spherical structure found in the center of the galaxy. This feature mostly contains older stars. The disk is made up of dust, gas, and younger stars. The disk forms arm structures. Our Sun is located in an arm of our galaxy, the Milky Way. The halo of a galaxy is a loose, spherical structure located around the bulge and some of the disk. The halo contains old clusters of stars, known as globular clusters<span>.
</span><span>
Elliptical galaxies are shaped like a spheriod, or elongated sphere. In the sky, where we can only see two of their three dimensions, these galaxies look like elliptical, or oval, shaped disks. The light is smooth, with the surface brightness decreasing as you go farther out from the center. Elliptical galaxies are given a classification that corresponds to their elongation from a perfect circle, otherwise known as their ellipticity. The larger the number, the more elliptical the galaxy is. So, for example a galaxy of classification of E0 appears to be perfectly circular, while a classification of E7 is very flattened. The elliptical scale varies from E0 to E7. Elliptical galaxies have no particular axis of rotation.
</span>
Carbon atoms are extremely small and are one of the only atoms that are structurally stable enough to form various different kinds of macromolecules.
Answer:
A cell wall is a fairly rigid layer surrounding a cell located outside of the plasma membrane that provides additional support and protection. They are found in bacteria, archaea, fungi, plants, and algae. Animals and most other protists have cell membranes without surrounding cell walls.
Explanation:
Answer:
- <em>Brønsted-Lowry acid: HNO₂</em>
- <em>Brønsted-Lowry base: NH₃</em>
- <em>Conjugate acid: NH₄⁺</em>
- <em>Conjugate base: NO₂⁻</em>
Explanation:
The equation is:
<em>Brønsted-Lowry acids</em> are H⁺ donors.
<em>Brønsted-Lowry bases</em> are H⁺ acceptors.
Thus, on the left side, <em>HNO₂</em> is the acid and <em>NH₃ </em>is the base.
The <em>conjugate acids</em> and <em>conjugate bases</em> are on the right side of the equation.
The <em>conjugate acid</em> is the spieces that is formed after a base accepts the proton; thus it is <em>NH₄⁺</em>. A <em>conjugate acid</em> contains one more H atom and one more + charge than the base that formed it.
The <em>conjugate base</em> is the species that is formed after the acid donates its proton; thus, <em>NO₂⁻</em> is the <em>conjugate base</em>. A <em>conjugate base</em> contains one less H atom and one more - charge than the acid that formed it.
Summarizing:
- Brønsted-Lowry acid: HNO₂
