Questions

A battle was fought between Iran under the king Darius and the state of Greece in 490 B.C at Marathon near Athens. This battle is known as the 'Battle of Marathon' in World History.

Gautamiputra Satakarni has been described as the "destroyer of the Sakas, the Yavanas and the Pallavas".

Thiruvananthapuram, capital of Kerala has topped in city governance ranking of the Annual Survey of India’s City Systems (ASICS) 2016 conducted by Janaagraha Centre for Citizenship and Democracy. This year it was the fourth edition the annual survey which had evaluated 21 major cities from the 18 states. It highlighted inadequacies in urban governance that could affect public service delivery and quality of life.

llanos is a tropical grassland while the remaining three are temperature grasslands

In chemistry, the term transition metal has three possible meanings: The IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell".

Any of the set of metallic elements occupying a central block (Groups IVB–VIII, IB, and IIB, or 4–12) in the periodic table, e.g. iron, manganese, chromium, and copper. Chemically they show variable valency and a strong tendency to form coordination compounds, and many of their compounds are coloured.

Here in the given options, only iron (Fe) is a transition metal since Strontium is an alkaline earth, arsenic is a metalloid, hydrogen is (normally) a diatomic gas.