can we write isotopes of carbon in C-12,C-13,C-14 as well as in the form of 12C6 ,13C6 ,14

Yes, we can write isotopes of carbon in both ways.

1. C-12, C-13, C-14: This is a common way to represent isotopes. The letter "C" stands for the chemical element (in this case, carbon) and the number following it represents the atomic mass number (the total number of protons and neutrons in the nucleus).

2. 12C6, 13C6, 14C6: This is another way to represent isotopes, often used in scientific contexts. The number before the "C" is the atomic mass number, and the number after the "C" is the atomic number (the number of protons in the nucleus). In this case, "6" is the atomic number of carbon.

So, both notations are correct and interchangeable. They just present the information in a slightly different order.