Here is Googles eligibility test :

    A Bachelors degree in Engineering with a good academic record .
    Good knowledge in internet , web-search, online advertising , numerical analysis ,fraud detection and e-commerce .
    Good written, verbal and interpersonal communication skills and ability to communicate clearly and efficiently .
    There are various sections included in the test during test conduction . Various sectionsare :
    Questions from computer awareness
    Verbal reasoning
    Quantitative aptitude
    Critical reasoning
    And the standard of the questions depends upon the nature of the post .
    The candidates who clear the written test are further called up for the interview .
    There is a psychometric test , which is conducted to identify the personality, behaviour ,social activities , qualities and values of the candidates. Candidate who is selected after the psychometric test will be then called for a technical interview.

After technical interview , there will be HR interview which includes some personal questions.

Good Luck!