Food additives:
These are the chemicals added to food for specialized functions as a preservatives, colourants, artificial sweeteners, flavour enhancers, Antioxidants.

Acid dyes:
1. These dyes are acidic in nature and used for dyeing animal fibres and synthetic fibres.
2. These can be used for protein fibres such as wool and silk.
3. Eg: Picric acid, Naphthol yellow-s.
Basic dyes:
1. These are basic dyes containing basic groups. (-NH₂, -NHR, -NR₂).
2. They are used for dyeing animal fibres and plant fibres.
Mordant dyes or Indirect dyes: 
1. Mordant is a substance which can be fixed to the fibre and then can be combined with the dye to form an insoluble complex called lake.
2. Aluminium, chromium and Iron salts are widely used as mordants
3. Eg: Alizarin
Direct dyes:
1. They have high affinity for cotton, rayon and other cellulose fibre. So they are applied directly as they fix firmly on the fabric
2. Eg: Congo red
Vat dyes:
1. It can be used only on cotton, not on silk and wool, this dyeing is a continuous process and is carried out in a large vessel called vat. So it is called as vat dye.
2. Eg: Indigo

1. In Daniel cell zinc metal acts as anode and copper metal acts as cathode .
2. Aqueous zinc sulphate solution makes the anodic electrolyte. Whereas aqueous copper sulphate solution makes the cathodic electrolyte.
3. Saturated solution of potassium chloride (KCI) acts as salt bridge .
4. At anode, zinc undergoes oxidation losing its electrons .
. Zn_(S) ⟶ Z²⁺+ 2e^- (Oxidation)
5. At cathode, copper ions from cathodic electrolyte gain electrons at the surface of cathode and get reduced to copper metal.
Cu²⁺ + 2e^- ⟶ Cu_(S)(Reduction)
Net reaction,
Zn + Cu²⁺ ⟶ Zn²⁺ + Cu_(s)
6. Cell potential of Daniel cell is 1.1V

The pH of a crop land is 5. So it is acidic in nature. So we use ammonium nitrate and calcium phosphate, urea. They are basic in nature.

Sudha must take drugs like analgesics because it is the compounds which relieve all sorts of pains without the loss of consciousness.