Which of the following solutions have the same concentration?

a. 20 g of NaOH in 200 mL of solution

b.  0.5 mol of KCl in 200 mL of solution

c.  40 g of NaOH in 100 mL of solution

d.  20 g of KOH in 200 mL of solution

Options: 

1. a & b

2. a & c

3. a & d

4. b & c

(a, b)
(a) Molarity (M)=weight of NaOH×1000Molecular weight of NaOH×V(mL)=20×100040×200=2.5 M
(b) M=0.5×1000200=2.5 M
(c) M=40×100010×100=10 M
(d) M=20×100056×200=1.785 M
Thus, 20 g NaOH in 200 mL of solution and 0.5 mol of KCl in 200 mL have the same concentration.