What type of reaction is it , when 2-chloropentane loses HCl? and how
many different products can be formedthis way?

2-chloropentane is one of a general class of molecules known as alkyl
halides. The elimination reaction that occurs when an alkyl halide
loses its halogen and a hydrogen is called dehydrohalogenation. It can
be either an E1 or E2 type elimination reaction.

The product will be an alkene, either 1-pentene, cis 2-pentene, or
trans 2-pentene.

Because of Zaitsev's Rule, 2-pentene is preferred, and the trans form
is more stable than the cis form.


Dehydrohalogenation of alkyl halides
http://www.chem.ucalgary.ca/courses/350/Carey/Ch05/ch5-3.html

A chemistry exam question discussing this reaction (Question 2A)
http://www.chemistry.gatech.edu/class/1315/weck/answer_key.pdf

The Alkene family
http://members.aol.com/logan20/alkenes.html

Zaitsev's Rule
http://stezlab1.unl.edu/Chem251/alkenes-1/zaitsevs_rule.htm

Hydrocarbons configuration (discusses cis and trans pentene)
http://www.geocities.com/chemistry_with_dr_ng/a/OC01stereo.htm

Search strategy
2-chloropentane reaction
dehydrohalogenation
chloropentane 2-pentane

Please let me know if I can clarify this in any way.

goo explaination

De-hydration and pent-1,2-ene?