Answer: in order of increasing atomic number.
Explanation: Elements in the same group have similar chemical properties. This is because they have the same number of outer electrons and the same valency.
The subscript in a chemical formula is the number written next to the element at the bottom part. For example, the chemical formula of water is H₂O. The subscript of H is 2, while the subscript of O is 1. The subscript represents the number of a certain element in one particle of the compound. So, if you change the subscript, you also change the number of a certain element per compound. In other words, you change the ratio.
<em>From the above options, the best </em><em>Thermal insulator </em><em>will be a </em><em>Plastic cup.</em>
Option (b);
<u>Explanation</u>
Thermal insulators resist to conduct energy or reduction of heat transfer when objects come across in contact with radiation or higher heat object. To conduct energy we need metal or those materials which contain free electrons in it to move from one metal to another.
Plastic doesn't have metallic character so it will resist the heat up to some threshold. Mostly this material is used in separating two current-conducting material. There are many other examples of thermal insulator such as Rubber, fabrics, paper, wood, wool.
Fe O
2 3 is what i would put