A positively charged particle Q$1=+45$ nC is held at fixed position. A second charge Q$2$ of mass m $=3\mathrm{.}5$ mu g is located a distance d $=35$ cm directly above charge Q$1.$ The net force on Q$2$ is equal to zero. You may assume this system is close to the surface of the Earth. Calculate the magnitude of Q$2$ in units of nanocoulombs.