**641. The unit vector in the direction of vector A = 2 i^ -2j^ + k^ is_______________?**

A. 2i^ – 2j^ + k^

B. (2i^ – 2j^ +k^)/9

**C. (2i^ – 2j^ +k^)/3**

D. (2i^ – 2j^ +k^)/5

**642. The cross product of two vectors is a negative vector when______________?**

A. They are parallel vectors

B. They are anti parallel vectors

C. They are a perpendicular vector

**D. They are rotated through 270°**

**643. In which quadrant, the only value of tan will be positive ?**

A. First

B. Second

C. Third

**D. Both 1st and 3rd**

**644. The magnitude of i^. (j^ x k^) is________________?**

A. 0

**B. 1**

C. -1

D. i^

**645. If A=Ax i^ + Ay j^ + Az K^ B = Bx i^ + By j^ + Bz K^ then______________?**

**A. A. B = Ax Bx + Ay By + Az Bz**

B. A. B = Ax By + Ay Bz + Az By

C. A. B = Ay Bz + Az By + Az Bx

D. A. B = Ax Bz + Ay By + Az Bx

**646. A central force is that which__________________?**

A. Can produce torque

**B. Cannot produce torque**

C. Some time can produce torque some time cannot

D. Has no relation with torque

**647. What is the angle that the given vector makes with y-axis and A=2i+3j ?**

A. 30°

**B. 60°**

C. 90°

D. 120°

**648. In which quadrant the two rectangular components of a vector have same sign ?**

A. 1st

B. 2nd

**C. Both 1st and 3rd**

D. 4th

**649. Two vectors A and B are making angle θ with each other. The scalar projection of vector B on vector A is written as____________?**

**A. A.B/A**

B. A.B/B

C. A.cosθ

D. Both a and b are correct

**650. Two vectors are A = 3i^+2j^ -k^& B = 3i^-2j^ +k^ , then_____________?**

A. B is anti-parallel to A

**B. B is a negative vector of A**

C. B has a negative magnitude

D. B is perpendicular to A