Which one of the following statements is NOT correct?
Hydrogen has no isotopes.
Understanding Hydrogen Properties
Let's analyze each statement about Hydrogen to determine which one is NOT correct.
Statement 1: Hydrogen is an element.
This statement is correct. Hydrogen is the chemical element with the symbol H and atomic number 1. It is the first element in the periodic table.
Statement 2: Hydrogen is the lightest element.
This statement is also correct. With an atomic mass of approximately 1.008 atomic mass units (amu), hydrogen is the lightest element.
Statement 3: Hydrogen has no isotopes.
This statement is NOT correct. Hydrogen has several isotopes. The most common is Protium (\(^1\)H), which has one proton and no neutrons. However, hydrogen also exists naturally as Deuterium (\(^2\)H or D), which has one proton and one neutron, and Tritium (\(^3\)H or T), which has one proton and two neutrons. Tritium is radioactive.
Therefore, the statement that hydrogen has no isotopes is false.
Statement 4: Hydrogen and oxygen form an explosive mixture.
This statement is correct. A mixture of hydrogen gas (\(H_2\)) and oxygen gas (\(O_2\)) is highly flammable and can explode when ignited. The reaction is:
\[2H_2(g) + O_2(g) \rightarrow 2H_2O(l) + Energy\]
This reaction releases a significant amount of energy, often resulting in an explosion when the gases are mixed in appropriate proportions (typically 2 parts hydrogen to 1 part oxygen by volume, or within the flammability limits).
Identifying the Incorrect Statement
Based on the analysis:
- Statement 1 is correct.
- Statement 2 is correct.
- Statement 3 is NOT correct (Hydrogen has isotopes).
- Statement 4 is correct.
The statement that is NOT correct is "Hydrogen has no isotopes."
Revision Table: Hydrogen Facts
| Property/Statement | Correctness | Explanation |
|---|---|---|
| Hydrogen is an element. | Correct | It is element number 1 on the periodic table. |
| Hydrogen is the lightest element. | Correct | It has the lowest atomic mass. |
| Hydrogen has no isotopes. | Incorrect | It has isotopes like Protium (\(^1\)H), Deuterium (\(^2\)H), and Tritium (\(^3\)H). |
| Hydrogen and oxygen form an explosive mixture. | Correct | The reaction \(2H_2 + O_2\) is highly exothermic and can cause an explosion. |
Additional Information: Hydrogen Isotopes and Properties
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Hydrogen's isotopes are particularly well-known:
- Protium (\(^1\)H): The most abundant isotope (over 99.98% of natural hydrogen). It has 1 proton and 0 neutrons.
- Deuterium (\(^2\)H or D): Also called "heavy hydrogen." It has 1 proton and 1 neutron. It makes up a small percentage of natural hydrogen and is used in heavy water (\(D_2O\)).
- Tritium (\(^3\)H or T): A radioactive isotope with a half-life of about 12.32 years. It has 1 proton and 2 neutrons. It is produced in nuclear reactors.
Hydrogen is a highly reactive element, especially under certain conditions. Its reaction with oxygen is a classic example of its high energy potential, used in applications like rocket fuel.
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Select the correct answer using the code given below :
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Important Questions from Basic Concepts of Chemistry
Which of the following pair is correct?
I. Isotopes – different mass numbers
II. Isobars – different atomic numbers
Which of the following is a zone of a flame?
I. Dark
II. Luminous
III. Non-Luminous
Sphalerite is an ore of:
If formula of sodium salt of an anion X is \(Na_2X\) , then the formula of its aluminium salt would be
Which of the following set contains same number of molecules?
A. 1 gram O 2, 2 grams SO 2
B. 1 gram CO 2, 1 gram N 2O
C. 1 gram O 2, 1 gram O 3
