22-yes, they belong to the same group
23- they are metals
24-Atoms of group 1 elements all have one electron in their outer shell. This means Na and K have the same valence electrons.
25-Metals are solids at room temperature, therefore Na and K are solid.
26- mass number=A=235
Protons=z=92
Neutrons=mass number-protons
Neutrons=A-Z
Neutrons=235-92
Neutrons=143
        
             
        
        
        
The mole fraction of pentane in the vapor is 0.291
Vapour pressure rises with temperature and is a measurement of a substance's propensity to transform into a gaseous or vapour state. The boiling point of a liquid is the temperature at which the pressure exerted by its surroundings equals the vapour pressure present at the liquid's surface. 
The number of moles of a particular component in the solution divided by the overall number of moles in the sample solution is known as the mole fraction.
Using the formula for vapour pressure,
vapour pressure =  °
° ×
 ×  +
 +  °
° ×
 × 
vapour pressure = 151 ×  

 + 425 ×
 + 425 × 
240 = 151 - 151 + 425
 + 425
240 - 151 = -  151 + 425
 + 425 
89 = 274 
 =
 = 
0.291 = 
Therefore,  the mole fraction of pentane in the vapor is 0.291
Learn more about vapour pressure here;
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Amount of silver nitrate taken = 269.μmol 
Volume of the solution = 300. mL
Concentration of a solution is generally expressed in terms of molarity. Molarity is defined as the moles of a substance present per liter of the solution. 

We want the concentration in millimoles/L. 
Converting μmol to millimol solute:
 μ
μ = 0.269 millimol
 = 0.269 millimol
Volume from mL to L: 
Therefore concentration of the chemist's solution = 
 
        
             
        
        
        
Answer:
 reee, here is your answer.
Explanation: CH3OH(l) + 3O2(g) rightarrow CO2(g) + 3H2O(g) CH3OH(l) + O2(g) rightarrow CO2(g) + 2H20(g) CH3OH(l) + 2O2(g) rightarrow 2CO2(g) + 4H20(g) 2CH3OH(l) + 3O2(g) rightarrow 2CO2(g) + 4H20(g) Correct Calculate Delta H degree rxn at 25 degree C.
 
        
             
        
        
        
The correct answer is, tobacco.