A dichotomous key helps you identify unknown specimens based on their traits because there are only two options available per trait. Selecting one from the two options (usually contrasting characteristics) from each step leads to smaller and smaller groups until the option is reduced to single and unique trait of an organism.
Considering you need to identify an organism. So, on the top of they key is animal with options: (a) with red blood cells and (b) no red blood cells. The option you will select is no red blood cells and under option b, you’re given two choices again: (a) hard bodies and (b) soft bodies. You’ll select soft bodies, then two options again are given: (a) with shell and (b) without shell. The option you’ll select would be without shell, and so on.
Answer:
C.) crystalline solids
Explanation:
The solid materials may be crystalline or amorphous. The concept of crystal structure is related to the organization of atoms in a geometrical form. Crystalline structures are present in various materials, where atoms distributed within their structure form a network called the crystalline lattice. Therefore, crystalline structures have salts, metals and most minerals. Crystalline structures are formed by unit cells that are their basic unit, as they constitute the smallest set of associated atoms found in a crystalline structure.
The molecules of the crystalline structures can have two types of bonds, the directional ones, which include the covalent and dipole dipole and the non-directional ones where the metallic, ionic, van der Walls bonds. When formed by ionic compounds, these crystalline structures can result in crystalline solids.
The correct answer is - A. A few centimeters a year.
Earth's crustal plates move very slowly, between 2 cm and 5 cm (depending on the plate) annually. This is the reason why it takes millions of years for them to significantly change their position, and with it the appearance of our planet. These crustal plates are slowly moving around the planet because they are powered by flow in the interior mantle.
