Being a foreign trained lawyer and being permitted to sit for Bar examination in the United States, if successful,I will practice law in the United States as Attorney at law. I am a Canadian Citizen and a permanent resident of the United States. Can I sit for Bar exam in Canada. Or Can I be admitted on motion once I become a practicing lawyer in the United States.

No. It is quite different north of the US border. Have a look on the website of the law society in the Canadian province that you intend to practise. Bonne Chance!