Answer:
<h2>chemoautotrophs</h2>
Explanation:
Such types of bacteria that oxidize inorganic compounds to obtain energy and use carbon dioxide as a carbon source to synthesize their food are known as chemoautotrophs such as iron-oxidizing bacteria, cyanobacteria, sulfur-oxidizing bacteria and some other. Chemoautrophic mode of nutrition is a type of autotrophic nutrition in which organisms have the ability to synthesized their own food by using chemical energy in the place of solar energy. The organismS that use solar energy to synthesize their food are known as photoautotrophic organisms such as plants and some other organisms.
Answer: The correct option is 3.
Explanation: We are given a compound which is made up of iron and oxygen only. The ratio of the two are given as:
This means that, number of iron ions are 2
Number of oxide ions are 3
From the above information, the formula becomes : 
The valency of iron = 3
Valency of oxide = 2
This compound is named as iron (III) oxide.
Hence, the correct option is 3
You can put it in a very strong magnetic field.
Answer:
A. The lens spreads light.
Explanation:
The convex lens will converge the light that passes through it. The direction of light will be bend to be closer to the middle point. This is the lens used for the eyeglass that treat people with hypermetropia. That is why the convex lens also called a converging lens or a plus lens. The strength of the convex lens depends on its focal length, index of the material used, and the radius of curvature.
