Concept:The kink in a clinical thermometer is a narrow constriction that controls the movement of mercury after the thermometer is removed from the patient.
Explanation:The kink prevents mercury from flowing back into the bulb immediately after use.
Thus, the mercury column stays at the highest temperature reached.
This allows the recorded temperature to be read after the thermometer is taken away from the patient.
So statement i is correct because it stops the back flow of mercury.
Statement iv is also correct because it lets the temperature attained be read later.
Statement ii is wrong because the kink does not ensure back flow of mercury.
Statement iii is wrong because the kink does not maintain the thermometric property of mercury.
Therefore, the correct pair is i and iv only.
Answer:C. i and iv only