Solution:

Assertion (A): For practical purposes in circuit analysis and grounding, the Earth's electric potential is taken as zero because it is a large conductor and can absorb or supply charge without significant potential change. So (A) is true.

Reason (R): The electric field strength on the Earth's surface is generally not zero; it varies due to atmospheric conditions, presence of charges, etc. So (R) is false.nTherefore, (A) is true and (R) is false.