Carbon-12 and carbon-13 are isotopes of carbon. which of the following statements is correct? they both have seven protons in the nucleus. they both have the same mass number. they both have seven neutrons in the nucleus. they both have the same atomic number.

We know that :

The Mass Number of an Element is the Sum of Neutrons and Protons.

The Atomic Number is the Number of Protons in the Nucleus of the Element

Carbon - 12 :

It has 6 Protons

It has 6 Neutrons

Mass Number of Carbon -12 is (6 + 6) = 12

Atomic Number of Carbon - 12 = 6

Carbon - 13 :

It has 6 Protons

It has 7 Neutrons

Mass Number of Carbon - 13 is (6 + 7) = 13

Atomic Number of Carbon -13 is 6

So, The Correct Answer is :

 They both have the same Atomic Number    

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a