1. Packaged foods are purged with nitrogen gas in order to prevent their oxidation.
2. Tooth decay starts when pH of the mouth is lower than 5.5.
3. The reactivity of metals decreases in the order : Mg > Fe > Zn.
Which of the statements given above is/are not correct ?
3 only
Let's analyze the given statements one by one to determine which is/are not correct:
- Statement 1: "Packaged foods are purged with nitrogen gas in order to prevent their oxidation."
- In food packaging, nitrogen gas is often used as a filler to replace oxygen. This is because nitrogen is an inert gas and does not react with the food, thus preventing oxidation, which can spoil food. Therefore, this statement is correct.
- Statement 2: "Tooth decay starts when pH of the mouth is lower than 5.5."
- Tooth decay is caused by acid-producing bacteria that thrive in more acidic environments. A pH less than 5.5 causes the enamel, the protective outer layer of the teeth, to demineralize. Therefore, this statement is correct.
- Statement 3: "The reactivity of metals decreases in the order: Mg > Fe > Zn."
- The correct order of reactivity for the metals mentioned is: Mg > Zn > Fe. Magnesium (Mg) is more reactive than both zinc (Zn) and iron (Fe). However, zinc is more reactive than iron. Thus, this statement is not correct.
Based on the analysis above, the statement that is not correct is:
- Statement 3
Therefore, the correct answer is 3 only.
Important Questions from Chemical Reactions
Which one of the following nitrogen oxides may dimerize?
The chemical formula of glucose is C6H12O6. The weight % of carbon in glucose is:
For a chemical reaction with rise in temperature by 10°, the rate constant becomes nearly ____________________.
A chemical reaction in which the rate of reaction is directly proportional to the first power of the concentration of the reacting substance is called:
What is the product formed when zinc and sulphuric acid react?
