just answer question 4 pls

1. What is the quanternion that would rotate this vector by 90 degrees around the z-axis? 2. What quaternion would rotate this vector by 90 degrees around the y-axis? 3. What will we have by rotating vector v using the quaternion in question 1 and then using the quaternion in question 2 ? 4. What is the quaternion that achieves the same rotation results by combining quaternion in question 1 and 2 ? In other words, what quaternion can we use to rotate the vector v to the result of question 3