Which one of the following is most acidic?

Let $a \neq 0$ and $p(x)$ be a polynomial of degree greater than $2$. If $p(x)$ leaves remainders $a$ and $-a$ when divided respectively by $x+a$ and $x-a$,then the remainder when $p(x)$ is divided by $x^2-a^2$ is:

The equation of the line joining the centres of the circles belonging to the coaxial system of circles $4x^2 + 4y^2 - 12x + 6y - 3 + \lambda(x + 2y - 6) = 0$ is

The poling process is used when the metal contains:

$A$ machine gun fires a bullet of mass $40\, g$ with a velocity $1200\, m/s$. The man holding it can exert a maximum force of $144\, N$ on the gun. How many bullets can he fire per second at the most?

The number of solutions $(x, y, z)$ to the system of equations $x+2y+4z=9$,$4yz+2xz+xy=13$,$xyz=3$,such that at least two of $x, y, z$ are integers is