Chakor Web Application Developer interview questions

mostly question are from database but pretty simple.. anyone with the basic knowledge can easily answers these questions.

Written test: 1) Reversing string 2) difference between linked list and doubly linked list 3) sql query of second maximum highest salary 4) swap two numbers without using third variable Interview: 1) tell me about yourself 2) describe yourself in three words 3) there are 10 balls. 9 balls are of 4kg and 1 ball is of 3kg. Find that 3kg ball. You can check the weight of the balls in a scale (trazu) inly three times only. 4) how to cut a cake in 8 pieces by making only 3 cuts.