Which of the following is used as the abrasive`//`Polishing agent in fluoride toothpaste?

Options

A. `Na_(4)P_(2)O_(7)`
B. `Na_(2)H_(2)P_(2)O_(7)`
C. `Ca_(2)P_(2)O_(7)`
D. `Na_(5)P_(3)O_(10)`

Answer

3

Explanation

`Na_(4)P_(2)O_(7)` is mixed with starch and flavouring to make 'instant pudding' mixtures.
Disodium dihydrogen pyrophosphate `(Na_(2)H_(2)P_(2)O_(7))` mixed with `NaHCO_(3)` is used in bread making to leaven the bread, i.e., to make it rise. They react and evolve `CO_(2)` when heated together.
`Na_(2)H_(2)P_(2)O_(7)+2NaHCO_(3)rarrNa_(4)P_(2)O_(7)+2CO_(2)+2H_(2)O`
This is an easier way of making batches of bread than using yeast, and is used commercially.
Sodium tripolyphosphate
`(Na_(5)P_(3)O_(10))` serves as a water softener. It does this by forming a stable soluble complex with `Ca^(+)` and.`Mg^(2+)` This is called sequestration, and results, in the effective removal (masking ) of these ions which are responsible for hardness in water. Thus `Ca^(2+)` and `Mg^(2+)` ions do not form precipitates with `CO_(3)^(2-)` ions or with soap in its presence. It also makes the solution alkaline which helps dissolve grease and improves the action of detergent.