If ` hat i ,\ hat j ,\ hat k\ ` are unit vectors, then ` hat idot hat j=1` b. ` hat idot hat i=1` c. ` hat ixx hat j=1` d. ` hat ixx( hat jxx hat k)=1`

Explanation

`hati , hatj , hatk` are unit vectors and angle between each of them is `90°`

So, `cos Q = cos pi/2 = 0`

So (A) is false

Option (B) is true because angle between them is `0°`

So, `cos = cos0 = 1`

(C) False as `hati × hatj = hatk`

(D) is False as `hatj × hatk = hati`

And then `hati × hati = 0` as `sin Q = 0`