I need some suggestion and helpful Links to study and give practice test for Magento Certification
You can take an example test set by Magestore by signing up here. Last time I used it it can track your progress, so everytime you take the test it stores your score so you can see if you are progressing your knowledge.
You can also read through the official Magento study guide which does give some example questions and tells you exactly what you will be tested on.
There are some exam sites which claim to have test papers but I think they are subscription and I'm not sure the legitimacy of the papers they have.