If the amplitude of $z-2-3i$ is $\frac{\pi}{4}$,then the locus of $z=x+iy$ is:

Which one of the following statements is wrong?

The system of equations $3x + 2y + z = 6$,$3x + 4y + 3z = 14$ and $6x + 10y + 8z = a$ has an infinite number of solutions if $a$ is equal to

If $200 \text{ MeV}$ of energy is released in the fission of one nucleus of ${}_{92}^{236}U$,the number of nuclei that must undergo fission to release an energy of $1000 \text{ J}$ is

Which of the following structures contains its own $DNA$?

Equations of the latus rectum of the ellipse $9x^2 + 4y^2 - 18x - 8y - 23 = 0$ are: