# For a first order reaction, $(A) \to products$, the concentration of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is :
( A ) $1.73 \times 10^{-5} M/min$
( B ) $3.47 \times 10^{-5} M/min$
( C ) $3.47 \times 10^{-4}M/min$
( D ) $1.73 \times 10^{-4}M/min$