The two vectors (say A and B) of different magnitudes cannot be combined to give zero resultant since minimum value of combination is ІA-BІ which is not zero if AB.
The three vectors A, B and C of different magnitudes can be zero such that they form a closed triangle, then,
A+B+C=0
or, C=-(A+B)
Hence, the sum of three vectors may be zero if vector sum of any two vectors is equal and opposite to the third vector.
Note: The vectors can give this result only if...
Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered more than the other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.

Omg,💓💓