The compound HClO4, when placed in water, will dissociate into the ions, H+ and ClO4-. Therefore, the 2.0 M solution will also form 2.0 M H+. The pH is calculated through the equation,
pH = -log[H+]
Substituting,
pH = -log[2] = -0.3
Thus, the pH of the solution is -0.3.
Answer:- 
Explanations:- The first reaction is combustion reaction as the hydrocarbon is burned in presence of oxygen to give carbon dioxide and water.
Second reaction is the synthesis reaction as in general a synthesis reaction looks like:

Third reaction is the decomposition reaction as it looks opposite of synthesis reaction.

In general, a single displacement reaction looks like:

Fourth reaction is single replacement reaction as bromine is replaced by chlorine.
So, the correct choice is the last reaction,
.
Answer:
A car stopped at the top of the hill
Explanation:
It's potenial energy because, the car could go down the hill and create kinetic energy. Hope this helps! Please give me brainly it is correct!
The mass of nitric acid required to make the given solution is 0.0627 g.
The given parameters:
- <em>Volume of the acid, V = 250 mL</em>
- <em>pH of the acid, = 2.4</em>
The hydrogen ion (H⁺) concentration of the nitric acid is calculated as follows;

The molarity of the nitric acid is calculated as follows;

The number of moles of the nitric acid is calculated as follows;

The molar mass of nitric acid is calculated as;

The mass of the nitric acid contained in the calculated number of moles is calculated as;

Thus, the mass of nitric acid required to make the given solution is 0.0627 g.
Learn more about molarity of acids here: brainly.com/question/13864682