Answer : (C) Hafnium is the most likely identity of the given substance.
Solution : Given,
Mass of given substance (m) = 46.9 g
Volume of given substance (V) = 3.5 
First, find the Density of given substance.
Formula used :
Now,put all the values in this formula, we get
= 13.4 g/
So, we conclude that the density of given substance (13.4 g/) is approximately equal to the density of Mercury and Hafnium (13.53 and 13.31 g/ respectively).
According to the question the substance is solid at room temperature but Mercury is liquid at room temperature. So, Mercury is not identical to the given substance.
Another element i.e, Hafnium is the element whose density is approximately equal to the given substance and also solid at room temperature. And we know that the melting point of solid is high.
So, Hafnium is the most likely element which is the identity of the given substance.
Keeps in heat, protects us from radiation, provides oxygen, and protects us from objects coming towards the earth.
Answer : Electron affinity (Eea) of an atom or molecule can be defined as the amount of energy released or spent when an electron is being added to a neutral atom or molecule in the gaseous state to form a negative ion.
Chlorine is considered to be the element which has highest electron affinity in the modern periodic table.
The general formula is X + 
----> 
+ energy
It is found that nonmetals have more positive Eea than metals.
Electron affinity increases across the group from left to right in the modern periodic table. Elements with small nucleus have high electron affinity.
Boiling I think! hope you get it right
