The reaction a → products is first order. if the initial concentration of a is 0.646 m and, after 72.8 seconds have elapsed, the concentration of a has fallen to 0.0146 m, what is the rate constant of the reaction?

0.00867 moldm-3

Explanation:

Since the reaction is 1st order,

Rate of reaction=∆[A]÷t

0.646-0.0146/72.8= 0.00867

Remember that in a first order reaction, the rate of reaction depends on change in the concentration of only one of the reaction species, A in the problem above.

first one is the correct answer

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.