A particle has velocity 2i+3j+5k and we have to prove that it is in 1D motion. The expert has posted the same answer 2 times. Now I am asking this for third time and kindly read the question again. The velocity of the particle is given not the position coordinates. The expert has posted the answer two times based on position coordinates. 

Dear Student ,
                        Whatever  answer given by expert is correct these velocities are not of 1D 
                        2i+3j is in 2D and  7i+3j+4k is in 3D  but if you want in one dimension
                         then along axises can be rsolved 
                       as 2i+3j 
                                      x-axis component 2m/s
                                      y-axis component 3m/s
                   and 7i+3j+4k
​                                     ​x-axis component 7m/s
                                      y-axis component 3m/s
                                    ​z-axis component 4m/s
                    and 2i+3j+5k
                                 x-axis component  2m/s
                                      y-axis component 3m/s
                                    ​z-axis component 5m/s

                                
Regard