To play a key role in your success in the initial phase, you should know that the Civil Services Aptitude Test Sample Question is important for the candidate as it is very much they need to practice enough before writing the actual exam. A serious dependent knows that the prelims With GS-I, aptitude paper called 'Civil Services Aptitude Test' (CSAT) CSAT paper is basically an aptitude test, where UPSC candidates skills, logical reasoning, analytical and communication skills, decision making, problem solving Assesses on solving, basic numerical ability and mental ability.