The position vector of a  moving  particle is given by $(3\widehat{i}+4t^2\widehat{j}-t^3\widehat{k})m$

$\left(a\right)\overrightarrow{r}=(3\widehat{i}+4t^2\widehat{j}-t^3\widehat{k})m;whent=0$

  $r=3\widehat{i}$[ i.e it starts from  $(3,0,0)$]

(b) $\overrightarrow{r}$when t = 1s is${\overrightarrow{r}}_1=(3\widehat{i}+4\widehat{j}-\widehat{k})$;$\overrightarrow{r}$ when t = 3 s is ${\overrightarrow{r}}_2=3\widehat{i}+36\widehat{j}-27\widehat{k}$ displacement  during t = 1s to 3s is $\overrightarrow{s}={\overrightarrow{r}}_2-{\overrightarrow{r}}_1=32\widehat{j}-26\widehat{k}$

 $\left(c\right)\overrightarrow{v}=\frac{dr}{dt}=8t\widehat{j}-3t^2\widehat{k}$component of velocity along x-axis at t = 2s is zero

$\left(d\right)\overrightarrow{a}=\frac{\overrightarrow{dv}}{dt}=8\widehat{j}-6t\widehat{k}$ acceleration is uniform along y - axis  acceleration is non-uniform  along z - axis