1. The deficiency of which one of the following leads to dental caries?

1. 1. Iron

   
   
   

   2. Copper

   
   
   

   3. Fluorine

   
   
   

   4. Zinc

   
   
   

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1. View Hint View Answer Discuss in Forum

   Fluorine

   Correct Option: C

   Fluorine

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2. Which one of the following noble gases is not found in the atmosphere?

1. 1. Argon

   
   
   

   2. Krypton

   
   
   

   3. Radon

   
   
   

   4. Xenon

   
   
   

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   Radon (Rn) is not found in the atmosphere.

   Correct Option: C

   Radon (Rn) is not found in the atmosphere.

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3. Which one of the following metals occurs in nature in free state ?

1. 1. Gold

   
   
   

   2. Sodium

   
   
   

   3. Aluminium

   
   
   

   4. Copper

   
   
   

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   Gold is a stable noble metal and resists the action of the atmosphere and occurs in free state.

   Correct Option: A

   Gold is a stable noble metal and resists the action of the atmosphere and occurs in free state.

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4. Which is the rarest naturally occurring element of earth?

1. 1. Gold

   
   
   

   2. Antimony

   
   
   

   3. Germanium

   
   
   

   4. Astatine

   
   
   

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   It is a radioactive element.

   Correct Option: D

   It is a radioactive element.

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5. Which one of the following elements exists in liquid state at room temperature ?

1. 1. Mercury

   
   
   

   2. Lead

   
   
   

   3. Sodium

   
   
   

   4. Calcium

   
   
   

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1. View Hint View Answer Discuss in Forum

   Mercury exists in liquid state at room temperature.

   Correct Option: A

   Mercury exists in liquid state at room temperature.

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