Hi, Shazin,
Per this website:
http://www.salesforcegeneral.com/salesforce-articles/test-org-or-sandbox.html
"Access to test orgs can be requested via the Salesforce partner portal (you do have to register as a partner, but doing so is free). Just about any edition of Salesforce can be requested as a test org, and any special configurations that are needed (for example disabling the API or enabling Person Accounts) are requested by opening tickets. The biggest limitation to these test orgs is that their storage capacity is very limited. The result is that though they come with all of the Salesforce functions, they don’t always truly reflect real-world use cases."
Hope that helps,
Eric