Some on-line exercises for first conditional:

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/1cond1.htm

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/1cond2.htm

http://www.englishgrammarsecrets.com/firstconditional/menu.php

http://perso.wanadoo.es/autoenglish/gr.con1.p.htm

http://www.better-english.com/grammar/firstconditional1.htm

http://www.perfect-english-grammar.com/first-conditional-exercise-1.html

http://www.impact-english.com/members/Grammar_Practice/Always/test-grammar/gr_prac_form-Cond1.htm

 

Some on-line exercises for second conditional:

http://www.englishgrammarsecrets.com/secondconditional/menu.php

http://perso.wanadoo.es/autoenglish/gr.con2.p.htm

http://www.perfect-english-grammar.com/second-conditional-exercise-1.html

http://www.impact-english.com/members/Grammar_Practice/Always/test-grammar/gr_prac_form-Cond2.htm

 

And some on-line exercises for first vs. second conditional:

http://wwwedu.ge.ch/cptic/prospective/projets/anglais/exercises/condit1.htm

http://www.english-area.com/paginas/Firstandsecondconditional.htm

http://www.oup.com/elt/global/products/naturalenglish/int/a_grammar/unit09/neint_grammar09/

http://www.englishtenseswithcartoons.com/exercise/first_or_second_conditional_quiz