N=N0​e−λtlnN=lnN0​−λt​Differentiating w.r.t λ, we getN1​⋅dλdN​∣dλ∣or,∣Δλ∣​=0−t=NtdN​=NtΔN​​Here, N=3000−1000=2000∴∣Δλ∣=2000×140​=0.02