Q. Consider the following pairs:

1. Gallium → Melts at near room temperature
2. Mercury → Only metal liquid at room temperature
3. Tungsten → Highest melting point among metals
4. Francium → Longest-lived alkali metal isotope

Which of the above pairs are correctly matched?
Answer: 1, 2, and 3 only
Notes: Gallium melts at 29.7°C, so it can melt near room temperature. Mercury is the only metal liquid at room temperature. Tungsten has the highest melting point among metals. Francium is highly unstable and has very short-lived isotopes, making statement 4 incorrect.