Given
a=5i^−j^−3k^
So, ∣a∣=52+12+32=35
b=i^+3j^+5k^
So, 52+12+32=35
So, a⋅b=5−3−15=−13
Now finding the projection of a on b using the formula we get,
∣b∣a⋅b=−3513
And projection of b on a is given by,
∣a∣a⋅b=−3513
Note- The original answer key was dropped by NTA in Jee mains 1st feb 2023, here we have modified the options.