Match List I with List II and select the correct answer using the code given below the Lists: List I (Element) A. Li B. Na C. K D. Cs List II (Use) 1. Time keeper in atomic clocks 2 Batteries 3 Transfer of nerve impulses 4 Control of the water content in the blood Code: A B C D

The alkali metals have distinct industrial and biological roles. Lithium (Li) is widely used in the manufacture of rechargeable batteries, including lithium-ion and solid-state types [1]. Sodium (Na) is essential for maintaining fluid balance and controlling water content in the blood, as well as transmitting nerve impulses [1]. Potassium (K) is vital for biological systems, specifically playing a crucial role in the transmission of nerve impulses and cellular function [1]. Caesium (Cs) is the international standard for precise timekeeping, serving as the foundational component in atomic clocks due to its regular atomic oscillation frequency. Therefore, the correct matching is A-2 (Li-Batteries), B-3 (Na-Transfer of nerve impulses), C-4 (K-Control of water content), and D-1 (Cs-Time keeper in atomic clocks). Note that while both Na and K are involved in nerve and fluid functions, Na is primarily associated with extracellular fluid/water balance.

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 4: Electricity: Magnetic and Heating Effects > A step further > p. 58