A molecule is paramagnetic if it has unpaired electrons. Oxygen (\( O_2 \)) has two unpaired electrons in its molecular orbital configuration, making it paramagnetic. Other molecules listed (like \( N_2 \) and \( H_2 \)) do not have unpaired electrons, making them diamagnetic.
Thus, the correct answer is (A).
x mg of Mg(OH)$_2$ (molar mass = 58) is required to be dissolved in 1.0 L of water to produce a pH of 10.0 at 298 K. The value of x is ____ mg. (Nearest integer) (Given: Mg(OH)$_2$ is assumed to dissociate completely in H$_2$O)