Litmus paper turns red in acidic conditions whether its blue or red litmus ,its not NH3 (ammonia) , neither is it barium hydroxide (A) , sodium hydroxide (B) will make it blue or remain blue (depemding on type of paper used ) so it has to be D which is the chemjcal formula for acetic acid , hope this helps !
I believe the answer is B. Definitely not D or A, and C doesn't makes sense.
Metals such as iron, nickel and cobalt are detected by passive and active metal detectors. Other metals, such as copper, brass and aluminum, are detected only by active means.
A large fraction of a specific source is used up.
