Answer:
Explanation:
A is Magnesium, B is Aluminium both are adjacent element and lie in third period.
Magnesium with atomic number of 12 consist two s electrons in it's valence shell in ground state whereas, Aluminium which has atomic number of 13 consist three electrons in it's valence shell in the ground state out of which two are s electrons and only one p electron.
Because you won’t have enough time to stop and bounce back up before you hit the ground since the cord is the same length as the building.
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.
The finagling in the hole