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Assertion: The deficiency of fluoride in...

Assertion: The deficiency of fluoride in drinking water cause disease such as tooth decay etc.
Reason: The `F^(-)` ions make the enamel on teeth much harder by converting hydroxyapatite, the enamal on the surface of the teeth, into much harder fluorapatite.

A

If both assertion and reason are true and the reason is the correct explanation of the assertion.

B

If both assertion and reason are true and the reason is not the correct explanation of the assertion.

C

If assertion is true but reason is false.

D

If assertion is false but reason is true.

Text Solution

Verified by Experts

The correct Answer is:
A
`[3(Ca_(3)(PO_4)_(2) gt Ca(OH)_(2)] underset(F^(-))(rarr) [3Ca_(3)(PO_4)_(2).CaF_(2)]`
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Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts Tooth decay starts when the pH of the mouth is lower than 5.5. Tooth enamel, made up of calcium hydroxyapatite (a crystalline form of calcium phosphate) is the hardest substance in the body. It does not dissolve in water, but is corroded when the pH of the mouth is below 5.5. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. The best way to prevent this is to clean the mouth after eating food. Using toothpastes, which are generally basic, for cleaning the teeth can neutralise the excess acid and prevent tooth decay. What should be the pH of the mouth to prevent damage to the teeth ?

The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to make teeth enamel harder by converting [3 Ca_3(PO_4)_2. Ca(OH)_2] to

Knowledge Check

  • F^(-) ions make enamel on teeth harder by converting hydroxy apatite into

    A
    `Ca_(3)(PO_(4))_(2)`
    B
    `Ca_(3)(PO_(4))_(2) CaFCl`
    C
    `3Ca_(3)(PO_(4))_(2) CaF_(2)`
    D
    `Ca_(3) (PO_(4))_(2) CaO F_(2)`

  • Deficiency of (F^(-)) in drinking water causes tooth decay. Its International Standard limit makes the enamal on tooth much harder by comverting hydroxyapatite into much harder

    A
    `Ca_(3)(PO_4)_(2).CaF_(2)`
    B
    `Ca_(3)(PO_4)_(2).3CaF_(2)`
    C
    `3Ca_(3)(PO_4)_(2).CaF_(2)`
    D
    `3Ca_(3)(PO_4)_(2).3CaF_(2)`

  • Fluoride deficiency in drinking water causes tooth decay blue baby syndrome Choose the correct option.

    A
    Only I
    B
    Only II
    C
    Only III
    D
    I and II

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    The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to make teeth enamel harder by converting [3Ca_(3)(PO_(4))_(2).Ca(OH)_(2)]

    The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to make teen enamel harder by converting [3Ca_(3) (PO_(4))_(2). Ca(OH)_(2)] to :

    Assertion : Soluable fluoride is often added to drinking water to bring its concentration up to 1 ppm. Reason : F^(-) ion concentration above 2 ppm causes brown mottling of teeth.

    Statement-1: Deficiency of fluoride in drinking water is harmful to human being. and Statement-2: Fluoride concentration more than 10 ppm causes harful effect to bones and teeth.

    When fluoride ion concentration in water is more than 2 ppm them it causes I. tooth decay II. brown mottling of teeth III. harmful effect to bone Identify the correct option.

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