6.0221367 rounded from the last digit would be 6.022137 but when using it calculations, you should just use 6.022 x 10^23.
Answer : The value of equilibrium constant (K) is, 424.3
Explanation : Given,
Concentration of
at equilibrium = 0.067 mol
Concentration of
at equilibrium = 0.021 mol
Concentration of
at equilibrium = 0.040 mol
The given chemical reaction is:

The expression for equilibrium constant is:
![K_c=\frac{[CH_3OH]}{[CO][H_2]^2}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BCH_3OH%5D%7D%7B%5BCO%5D%5BH_2%5D%5E2%7D)
Now put all the given values in this expression, we get:


Thus, the value of equilibrium constant (K) is, 424.3
Answer : The correct option is, (b) 22.5 M
Explanation : Given,
Mass of calcium nitrate tetrahydrate = 266 g
Molar mass of calcium nitrate tetrahydrate = 236.15 g/mole
Volume of solution = 
Molarity : It is defined as the moles of solute present in one liter of solution.
Formula used :

Now put all the given values in this formula, we get:

As calcium nitrate tetrahydrate dissociate to give 1 mole of calcium ion, 2 moles of nitrate ion and 4 moles of water.
The concentration of nitrate ion = 
Thus, the concentration of nitrate ion is, 22.5 M
In this question, you are given the wine/alcohol concentration (12%) and the volume of the alcohol(0.75l). You are asked the alcohol content in milli liters, so don't forget to change the unit. Then the equation would be:
Alcohol content= alcohol concentration * bottle volume
Alcohol content = 12%* 0.75l * 1000ml/l= 90ml
Answer: The kilograms of water must evaporate from 8kg of a 25% salt solution to produce 40% salt solution is 3 kg.
Explanation:
According to the ratio and proportion:

where,
= concentration of ist solution = 25%
= mass of ist solution = 8 kg
= concentration of second solution = 40%
= mass of second solution = ? kg


Thus the final solution must have a mass of 5 kg , i.e (8-5)= 3 kg of mass must be evaporated.
Therefore, the mass that must be evaporated from 8kg of a 25% salt solution to produce 40% salt solution is 3 kg.