If `|(a,b,0), (0,a,b), (b,0,a)|=0,` then which one of the following is correct?

If vec(a) and vec(b) are two vectors such that vec(a).vec(b) = 0 and vec(a) xx vec(b) = 0 , then which one of the following is correct?

If vec(a). vec(b) = 0 and vec(a) xx vec(b) = vec(0) then which one of the following is correct ?

If A=[{:(0,1),(-1,0):}] B=[{:(i,0),(0,-i):}] C=[{:(0,-i),(-i,0):}] then which one of the following is not correct ?

If A=[{:(0,1),(-1,0)],B=[{:(i,0),(0,-i):}],C=[{:(0,-i),(-i,0):}] , then which one of the following in not correct ?

If A =({:(i,0),(0,-i):}),B=({:(0,-1),(1,0):}),C=({:(0,i),(i,0):}) wher i = sqrt(-1) , then which one of the following is correct ?

If |{:(a,b,0),(0,a,b),(b,0,a):}| = 0, (a ne 0 ) then