To study chemical properties of elements, Mendeleev concentrated on their compounds formed by which two elements?

Correct option is A

Sol: The correct answer is (a) H and O

Key points:

Dmitri Mendeleev, while developing his Periodic Table, focused on the chemical properties of elements by studying their compounds formed with hydrogen (H) and oxygen (O). These two elements were chosen because:

1. Hydrogen and oxygen form compounds with most elements, making them ideal for comparison across a wide range of elements.
2. The compounds of elements with hydrogen (e.g., HCl, H2S) and oxygen (e.g., oxides like CO2, SO2) exhibit distinct chemical properties that help classify elements.
3. These properties provided clues about valency, reactivity, and periodic trends, which were crucial for grouping elements in the periodic table.

This focus on hydrogen and oxygen was instrumental in identifying periodic patterns and organizing elements into groups and periods based on their properties.

Information booster:

1.  N and Cl: Nitrogen and chlorine form specific compounds but are less universal than hydrogen and oxygen for periodic trends.
2.  O and S: Oxygen is key for classification, but sulfur is less representative and not as versatile.
3.  C and H: Carbon’s compounds are mostly organic and not broad enough for periodic classification, unlike hydrogen and oxygen.