Which artery is absent in a frog?

Along the $X$-axis,three charges $\frac{q}{2}, -q$ and $\frac{q}{2}$ are placed at $x=0, x=a$ and $x=2a$ respectively. The resultant electric potential at $x=a+r$ (if $a \ll r$) is: ($\varepsilon_0$ is the permittivity of free space)

The equation of the normal to the curve $y=x \log x$,which is parallel to the line $2x-2y+3=0$,is

The solution of $(x^2+y^2) dx = 2xy dy$ is:

If the bond length and dipole moment of a diatomic molecule are $1.25 \ \mathring{A}$ and $1.0 \ D$ respectively,what is the per cent ionic character of the bond?

Choose the correct statement$(s)$:
$(A)$ The position of the centre of mass of a system is dependent on the choice of the coordinate system.
$(B)$ Newton's second law of motion is applicable to the centre of mass of the system.
$(C)$ Internal forces cannot change the state of the centre of mass.
$(D)$ Internal forces can change the state of the centre of mass.