After a quick analysis I can see that you missed a comma between '$income' and now() at the end of the statement. A good way to find errors in your sql statements is to always check the returned value and echo mysql_error() if it failed. It would have probably told you that the error was near '$income' which probably would have lead you to notice this error youself. 🙂
$is_success_second = mysql_query("insert into data (username, password, firstname, lastname, email, age, sex, country, occupation, industry, zip, passquest, passans, income, date) values ('$username', '$password', '$firstname', '$lastname', '$email', '$age', '$sex', '$country', '$occupation', '$industry', '$zip', '$passquest', '$passans', '$income', now())");