The atomic number of Einsteinium (Es) is 99. The electronic configuration of an element can be determined by following the Aufbau principle, which fills the orbitals in the order of increasing energy.
The configuration for Einsteinium is $[\text{Rn}]5f^{11}6d^07s^2$, where:
$[\text{Rn}]$ represents the electron configuration of the nearest noble gas, Radon (86).
The $5f^{11}$ represents the 11 electrons in the 5f subshell.
The $6d^0$ indicates no electrons in the 6d subshell.
The $7s^2$ indicates the 2 electrons in the 7s subshell.
Thus, the correct answer is (2).
If the system of equations \[ x + 2y - 3z = 2, \quad 2x + \lambda y + 5z = 5, \quad 14x + 3y + \mu z = 33 \] has infinitely many solutions, then \( \lambda + \mu \) is equal to:}
The equilibrium constant for decomposition of $ H_2O $ (g) $ H_2O(g) \rightleftharpoons H_2(g) + \frac{1}{2} O_2(g) \quad (\Delta G^\circ = 92.34 \, \text{kJ mol}^{-1}) $ is $ 8.0 \times 10^{-3} $ at 2300 K and total pressure at equilibrium is 1 bar. Under this condition, the degree of dissociation ($ \alpha $) of water is _____ $\times 10^{-2}$ (nearest integer value). [Assume $ \alpha $ is negligible with respect to 1]