Answer:- C. Hafnium.
Solution:- Mass of the sample is 46.0 g and it's volume is 
.
From mass and volume, we can calculate it's density using the formula:
On the basis of the density, this substance could either be mercury or hafnium. Since the substance is a solid at room temperature where as mercury is liquid. So, it can't be mercury.
The right choice is C) Hafnium.
A 3.1 L sample of hydrogen <u>d. contains the same number of molecules</u>
as 3.1 L of carbon dioxide at the same temperature and pressure.
This is the fundamental principle of <em>Avogadro’s hypothesis</em>: equal volume of gases at the same temperature and pressure contain the same number of molecules.
The sample of carbon dioxide has a <em>greater mass</em>, a <em>greater number of atoms</em>, and a <em>greater density</em>, than the sample of hydrogen.
A mixture is easy to separate out into its parts because each part of the mixture keeps is molecular properties
