1. If the shortest wavelength of hydrogen atom in Lyman series is x, then longest wavelength in Balmer series of He⁺ is
a) $\frac{9x}{5}$
b) $\frac{36x}{5}$
c) $\frac{x}{4}$
d) $\frac{5x}{9}$

---

2. Which of the following has square planar structure?
a) $\left [NiCl_{4} \right ]^{2-}$
b) $\left [Zn\left (NH_{3} \right )_{4} \right ]^{2+}$
c) $\left [Ni\left (CO \right )_{4} \right ]$
d) $\left [Ni\left (CN \right )_{4} \right ]^{2+}$

---