The coefficients in a balanced chemical equation are important because they give the ratio of the reactants and the products.
Those ratios are fixed and when the reagents react do it in the same proportion and yield the products in the same proportion of the coefficients.
Then, the coefficients are the basis for the calculations of the amount of substances that react and the amount of substances that are formed as result of the reaction.
Oxygen<span> is a </span>chemical element<span> having a symbol </span>O<span> and having an </span>atomic number<span> 8.
Oxygen is a pure substance , and it is not a mixture or solution, Niether it is a compound ... Instead , it forms chemical compounds by reacting with other elements.
So , according to above explanation ,
A. A pure substance , is the correct answer.</span>
The most appropriate answer is D ! temperature !
as when temperature increases KE increases and the collision factor and frequency increases !
Here is the correct question
You mix 125 mL of 0.170 M CsOH with 50.0 mL of 0.425 M HF in a coffee-cup calorimeter, and the temperature of both solutions rises from 20.20 °C before mixing to 22.17 °C after the reaction. What is the enthalpy of reaction per mole of ? Assume the densities of the solutions are all 1.00 g/mL, and the specific heat capacities of the solutions are 4.2 J/g · K. Enthalpy of reaction = kJ/mol
Answer:
75.059 kJ/mol
Explanation:
The formula for calculating density is:

Making mass the subject of the formula; we have :
mass = density × volume
which can be rewritten as:
mass of the solution = density × volume of the solution
= 1.00 g/mL × (125+ 50 ) mL
= 175 g
Specific heat capacity = 4.2 J/g.K
∴ the energy absorbed is = mcΔT
= 175 × 4.2 × (22.17 - 20.00) ° C
= 1594.95 J
= 1.595 J
number of moles of CsOH = 
= 0.2125 mole
Therefore; the enthalpy of the reaction = 
= 
= 75.059 kJ/mol
Correct answer- B the electrons every two elements are arranged in energy levels: a maximum two electrons in the first level. ((( i thinkkk )))