Group 1 elements since they have one outermost electron which they can give to chlorine which has 7 outermost electrons in order to form a stable compound.
Example
Pottasium (K) + Chlorine (Cl) = Potassium Chloride (KCL)
For an object to sink in something, it's density has to be higher than the object it is in, so if it sinks in water the number has be higher than 1
And to float, and objects density has to be lower than that of the substance it is put in, so it has to be lower than 1.26
So between 1 and 1.26
C. Weak acid is the correct answer
Carbonic acid is produced when a strong acid reacts with the bicarbonate buffer system in the human body.