A arrow product (First order reaction). Three sets of experiment...

For a first-order reaction, rate = $k[A]$, where rate is directly proportional to reactant concentration.
Run 1: 100 mL of 10 M solution
Concentration = 10 M
Rate: $r_1 = k \times 10$
Run 2: 200 mL of 10 M solution
Concentration remains 10 M (increasing volume doesn't change concentration)
Rate: $r_2 = k \times 10$
Therefore $r_1 = r_2$
Run 3: 100 mL of 10 M solution + 100 mL of H₂O
Total moles of A = 10 M × 0.1 L = 1 mol
Total volume = 0.2 L
New concentration = 1 mol / 0.2 L = 5 M
Rate: $r_3 = k \times 5$
Therefore $r_3 < r_1 = r_2$