We will neither give the Hypertonic Solution nor the Isotonic Solution but the patient will be given an Hypotonic Solution.
<h3>Explanation:</h3>
As the patient is taken for heat stroke and has resulted in dehydration so it means that the water content in the cells of the patient has been decreased and the solute content is being increased. Hence, this case is known as <em>Hypertonicity</em>. So, in order to make the concentration of water and solute balance (<em>Isotonicity</em>) on both sides (inside and outside the cells) we should administer an <em>Hypotonic solution</em> into the patient body. Therefore, the higher concentration of solutes in cells will drag the water content from hypotonic solution and gradually the process will attain an isotonic environment.
The atomic radius of strontium is larger than magnesium because there are more number of shielding electrones in strontium than magnesium, which causes electron-electron repulsion, that makes the electrons in valance shell to expand. Hence it would decrease the effective nuclear charge.