(4) To reduce greenhouse gases Explanation: The Kyoto Protocol is an international treaty which extends the 19992 United Nations Framework Convention on Climate Change (UNFCCC) that commits State Parties to reduce green hourse gas emissions.
The lustre of the metals is because of – (1) high density, due to closed packing of atoms (2) high polish (3) reflection of light due to the presence of free electrons (4) absorption of light due to the presence of cavities