Yes, a physical quantity can have magnitude and direction but still be a scalar if it doesn't obey the vector addition. An example is Electric Current which has magnitude and a fixed direction, but it does not follow vector laws of addition.
According to the Heisenberg Uncertainty Principle, it is impossible to determine the exact spin of an electron at any given moment. The Uncertainty Principle states that the more precisely we know the position of a particle, the less precisely we can know its momentum, and vice versa. Spin is a form of intrinsic angular momentum, which means it does not correspond to any specific position in space, and therefore cannot be measured precisely at the same time as its position.
However, while we...
Yes, if the angle between the two vectors is more than 90o but less than 2700. (cosΘ is negative)
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