Explain the concept of residuary powers under the Indian Constitution. Why were they vested in the Parliament?

Residuary powers are those subjects that are not mentioned in any of the three lists. E.g. information security, computer software. Is borrowed from Canadian Constitution. The residuary powers are conferred vested upon the Parliament which makes the Indian constitution unitary in nature. Reasons for residuary powers being vested in the Parliament: (1) These subjects are new and evolving in nature and thus powers with respect to it are given to Parliament. (2) These subjects require uniform rules and implementation throughout India and so only centre is given the power to make laws on it. (3) Being vested in the Parliament, it ensures that no fragmented approach is being adopted and also any issues arising out of the litigation in these matters can be dealt with early. (4) It gives uniform identity to the nation on these + matters and also ensure easy collaboration with foreign nations with on these matters. (5) Also, allows centre to sign treaties and implement them uniformly. These residuary powers due to their evolving and pre-requisite for uniformity are vested in the Parliament.