I am having a doubt about installing Kali Linux. Can I install Kali Linux on USB. I am currently having windows 7 32 bit. The real doubt is can I run Kali Linux and windows simultaneously after one another with USB without dual boot.
Yes what you are looking for is possible and there plenty of documentation for it. Just run over to the official documentation.
And check out both articles.
I down voted you as a very simple search would have brought up the documentation.