For avoiding the reduction of the residual hardness, incomplete precipitation and slow reaction, The reaction is carried out at __________ temperature.

For avoiding the reduction of the residual hardness, incomplete precip

1.	For avoiding the reduction of the residual hardness, incomplete precipitation and slow reaction, The reaction is carried out at __________ temperature.
A.	30-40<sup>o</sup>C
B.	40-50<sup>o</sup>C
C.	50-60<sup>o</sup>C
D.	60-70<sup>o</sup>C
Answer» D. 60-70<sup>o</sup>C