Answer:
0.0125mol
Explanation:
Molarity (M) = number of moles (n) ÷ volume (V)
n = Molarity × Volume
According to this question, a 0.05M solution contains 250 mL of NaOH. The volume in litres is as follows:
1000mL = 1L
250mL = 250/1000
= 0.250L
n = 0.05 × 0.250
n = 0.0125
The number of moles of NaOH is 0.0125mol.
Answer:
C. 7.50g
Explanation:
The percent (%) by mass of a solute in a solution refers to the number of grams contained in 100g of solution by that solute. In this case, 5% by mass of pottasium chloride (KCl) means 5g of KCl is contained in 100g of solution.
Therefore, in 150g of solution, there would be:
5g/100g × 150g
= 0.05 × 150
= 7.50g of KCl solute.
Hence, 7.50g of pottasium chloride would be expected to be collected by evaporating 150.0 g of the solution.
Since chromium has 24 as its atomic number (which mean that it has 24 proton and 24 electron in neutral ground state), the electron configuration for the chromium would be :
1s^2 , 2s^2 , 2p^6 , 3s^2, 3p^6 , 3d^5 , 4s^1
