Find the oxidation number of chromium in K2Cr2O7

The oxidation state of chromium is +6

Explanation:

Let the oxidation number be x

Since The sum of all oxidation numbers are equal to zero,

So,

(+1)2 + 2x + (-2)7 = 0

+2 +2x -14 = 0

2x-12 = 0

2x = +12

Dividing 2 to both sides

x = +6

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.