The electronegativity of the given elements increases in the order.

The first ionisation enthalpies of $$\mathrm{Mg}$$ and $$\mathrm{Al}$$ can be expected to be ............ .

Which of the following statements is/are correct?

1. Mercury is the only metal that exists as liquid at room temperature.

2. Among non-metals, carbon has the highest melting point.

3. Hydrogen is the most abundant element in the universe.

4. Oxygen is the most abundant element in the Earth's crust.

The element with outer electronic configuration $$(n-1) d^2 n s^2$$, where $$n=4$$, would belong to