1.if 1/5^3y=0.008,then find the value of 0.25^y

Taking log on both sides we have

3y log(1/5) = log (0.008)

we can write 

3y log(0.2) = log(0.2³) or 3 log(0.2)

3y log(0.2) =3 log(0.2)

solving we get y = 1

hence 

0.25^y = 0.25¹ = 0.25