Which of the following statements is correct regarding the modern periodic table?
A. Noble gases are in Group 1.
B. There are 8 periods.
C. Elements in a group have same number of valence electrons.
D. It is based on atomic mass.
Answer: Option C
Solution (By JKExamLibrary)
Groups (vertical columns) contain elements with the same number of valence electrons, leading to similar chemical properties. The modern table is based on atomic number; 7 periods exist; noble gases are in Group 18.
Explanation:
Half-life (T₁/₂) is the time taken for the number of radioactive nuclei (or activity) to decrease to half of its original value. It's a constant characteristic of each radioisotope. For example, C-14 half-life is 5730 years.
Explanation:
Cathode rays consist of electrons, which are fundamental particles. Therefore, their nature (charge to mass ratio) is independent of the gas used in the cathode ray tube or the material of the cathode. All other statements are correct properties of cathode rays, demonstrating their fundamental particle nature.
Explanation:
Ant sting contains formic acid (methanoic acid, HCOOH). It causes a burning sensation. It can be neutralized by applying a mild base like baking soda. Acetic acid is in vinegar, citric acid in lemons, lactic acid in curd.
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