F2 IS about hair

1.

Conditioners are frequently acidic, as low pH protonates the amino acids, providing the hair with positive charge and thus more hydrogen bonds between hairs, giving the hair a more compact structure.

2.

Hair consists of approximately 97% of a protein called keratin.
The surface of keratin contains negatively-charged amino acids. Hair conditioners therefore usually contain cationic surfactants as their
hydrophilic ends strongly bind to keratin.
The hydrophobic ends of the surfactant molecules then act as the
new hair surface

3.

As there may be some residue of the conditioner which mixed with
the wastes. Also, the skin of human is slightly acidic. Thus, it may be sensitive to someone due to the alkality of the conditioner.

4.

I am not sure about this question so I hope somebody can help you.

1)This is because by adding acetic acid to make amphoteric surfactant change to cationic surfactant which is usually the main ingradient of hair conditioner. 2)The cationic surfactant can adhere to the hair to make it soft just as the laundary softener makes the clothes soft after washing. 3)You mean"throw"away shampoo--the shampoo is usually fully biodegradable product, it is rather green product, it would not hurt the enoviroment. 4)"perming"--is that you mean comb the hair.If you always twist the hair you could break it.