Answer : The volume of the cube is, 
Solution : Given,
Density of nickel = 
Number of nickel atoms = 
Molar mass of nickel = 58.7 g/mole
First we have to calculate the moles of nickel.
As,  atoms form 1 mole of nickel
 atoms form 1 mole of nickel
So,  atoms form
 atoms form  moles of nickel
 moles of nickel
The moles of nickel = 3.321 moles
Now we have to calculate the mass of nickel.


The mass of nickel = 194.94 g
Now we have to calculate the volume of nickel.



Therefore, the volume of the cube is, 
 
        
             
        
        
        
Answer:
chemical stability is important to consider in the comprehensive assessment of pharmaceutical properties, activity, and selectivity during drug discovery. 
 
        
                    
             
        
        
        
Answer:
The correct answer is a scientific law. 
Explanation:
The laws of science or scientific laws refer to the statements, which predict or illustrate an array of natural processes. It is a statement based on observations or spontaneous experiments, which illustrate some characteristics of the natural world.  
The term law exhibits different uses in various circumstances, that is, across all the branches of natural science. The laws are formulated through data and can be further created via mathematics, in all the conditions, they are indirectly or directly based on empirical evidence. The scientific laws recapitulate the outcomes of observations or experiments, generally within some point of application.  
 
        
             
        
        
        
Answer:
The wavelength of the line in the emission line spectrum of hydrogen caused by the transition of the electron for the given energy levels is 
Explanation:
Given :
The energy E of the electron in a hydrogen atom can be calculated from the Bohr formula:

 =  Rydberg energy
 =  Rydberg energy
n =  principal quantum number of the orbital 
Energy of 11th orbit = 

Energy of 10th orbit = 

Energy difference between both the levels will corresponds to the energy of the wavelength of the line which can be calculated by using Planck's equation.


 (Planck's' equation)
 (Planck's' equation)


The wavelength of the line in the emission line spectrum of hydrogen caused by the transition of the electron for the given energy levels is 
 
        
             
        
        
        
Answer:
- Question 19: the three are molecular compounds.
Explanation:
<em>Question 19.</em>
All of them are the combination of two kinds of different atoms in fixed proportions.
- C₂H₄: two carbon atoms per four hydrogen atoms
- HF: one hydrogen atom per one fluorine atom
- H₂O₂: two hydrogen atoms per two oxygent atoms
Thus, they all meet the definition of compund: a pure substance formed by  two or more different elements with a definite composition.
Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.
Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.
<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.
Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol
Water is H₂O. Its molar mass is 18.015g/mol
Calling x the number of water molecules in the hydrate, the percentage of water is: 
        
From which we can solve for x:
       
Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is: