Pgcet is the master degree for what you have done in your bachelor's degree in general. But most of the engineering branches are interdisciplinary . An ECE student will be knowing the concepts of EEE branch and also little programming and goes the same with other branches also. No doubt, you can appear for chemical engineering ! if you want to possess your career in CE. I feel like -Why don't you specialize yourself in a branch which you are familiar with? Well its upto you. :)

All the very best for your pgcet anyways:)

Regards,

Sirisha Sanatha