Some Basic Concepts of Chemistry: Class 11 Chemistry Q&A
3 free answers on Some Basic Concepts of Chemistry (Chemistry) for Class 11 students, across CBSE, ICSE and State boards. Includes questions such as “what is meant by a substance?”, “What formula is COOH?”
Question & Answer
Questions
- ChemistryClass 11CBSE
2.8×10⁻³ mol of CO₂ is left after removing 10²¹ molecules from its ‘x’ mg sample. Find x. (Nₐ = 6.02×10²³ mol⁻¹)
Molar mass of CO₂ = 44 g/molStep 1 — Convert removed molecules to moles:Moles removed = 10²¹ / (6.02×10²³) = 1.661×10⁻³ molStep 2 — Initial moles = remaining + removed:n_initial = 2.8×10⁻³ + 1.661×10⁻³ = 4.461×10⁻³ molStep 3 — Initial mass:mass = 4.461×10⁻³ × 44 = 0.19629 g = 196.3 mgAnswer: x ≈ 196.3 mgDividing molecule count by Nₐ gives moles; multiplying by molar mass gives mass the two-step core of all JEE mole-conce
- ChemistryClass 11All
what is meant by a substance?
In chemistry, a substance is a form of matter that has a specific chemical composition and distinct properties. Substances can be elements, compounds, or mixtures of elements and compounds. Here are some key points to understand about substances: Chemical Composition: A substance has a well-defined and constant chemical composition. This means it consists of a specific arrangement of atoms or molecules. Elements, for example, are substances composed of only one type o
- ChemistryClass 11All
What formula is COOH?
COOH is not a full formula by itself; it is a functional group known as the carboxyl group. It represents a combination of a carbonyl group (C=O) and a hydroxyl group (–OH) attached to the same carbon atom. This group is commonly written as –COOH in chemical structures. The COOH group is a defining feature of carboxylic acids, which are widely found in biology and chemistry. For example, acetic acid (CH₃COOH) contains one COOH group, while amino acids contain both an amine