The compound prepared by a substitution reaction of benzene is

Which one of the following statements about packing in solids is incorrect?

$A$ projectile is projected with velocity $k v_e$ in the vertically upward direction from the ground into space. ($v_e$ is the escape velocity and $k < 1$). If air resistance is considered to be negligible,then the maximum height from the centre of the Earth to which it can go will be: ($R =$ radius of Earth)

Which element is estimated by the Carius method?

The catalyst and promoter respectively used in the Haber's process of industrial synthesis of ammonia are

The number of solutions for the equation $x^2 - 5|x| + 6 = 0$ is