21. Which substance is a gas at 45 degrees C?* A. Ethanol O B. Hexane C. Methane O D. Methanol

C. Methane

Explanation:

A chemical equation can be defined as a reaction between two chemical elements.

For a chemical reaction (equation) to be balanced, the condition which must be met is that the number of atoms contained in the reactants must be equal to the number of atoms in the products.

This ultimately implies that, the mass and charge of the chemical equation are both balanced properly.

Methane is a hydrocarbon compound formed by the reaction between four (4) hydrogen atoms with a carbon atom. It belongs to the alkane group of hydrocarbons and has the following physical and chemical properties; colorless, highly flammable, non-toxic and odorless gas. The empirical formula for Methane is CH4.

Methane is a gas at 45 degrees celsius. This ultimately implies that, at 45°C methane is a gas because it is still within the range of standard temperature and pressure.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

a and b sometimes have a positive value