why scanf("%c", &ch ) do not read the character from console while scanf(" %c", &ch ) Does

Question

scanf("%c", &ch ) do not read the character from console while scanf(" %c", &ch ) does, the snipet from code is given under

printf("If the value of speed of sound is known enter Y else enter N");
scanf(" %c", &ch );

Answer 1

scanf(" %c", &ch );

This space before the %c is, probably, taking care of the buffered newline character. See [ this ] answer.