Answer:
1. False
2. True
3. False
Step-by-step explanation:
1. Metallic properties of the elements increase from left to right across a period or series.
Having Metallic properties means that the element is good at loosing electrons. The metallic properties decreases fro left to right across a period or series due to the decrease in radius of the atom in the periodic table.
2. The yet-to-be discovered element with an atomic number of 118 would be a noble gas.
Oganesson (Og) is the name given to this element which is a radioactive element having an atomic number of 118 and unknown melting and boiling point. It is expected to be a gas that's why it is placed in the noble gas group
3. An atom of oxygen is larger than an atom of lithium.
An atom of oxygen is smaller than an atom of lithium because oxygen has a nuclear charge of 8+ which is higher than that of lithium 3+. This higher nuclear charge means that the electrostatic attraction between electrons and nucleus is grater, which pulls the electrons closer to the nucleus resulting in a smaller radius.