The number of elements known at the time of Russian chemist Dmitri Ivanovich Mendeleev was.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e.63.
At the time Russian chemist Dmitri Mendeleev developed his periodic table in 1869, 63 elements were known.
- Mendeleev's Contribution: Dmitri Mendeleev is credited with organizing the known chemical elements into a periodic table, which arranged elements by their atomic weight and chemical properties.
- Elements Known at the Time: When Mendeleev published his periodic table, 63 elements were known to scientists.
- Mendeleev's Periodic Table: Mendeleev's periodic table was a vertical chart that organized 63 known elements by atomic weight, placing elements with similar properties into horizontal rows.
- Prediction of Unknown Elements: Mendeleev's periodic table also allowed him to predict the existence and properties of elements that were not yet discovered, such as gallium, scandium, and germanium.