First year science students 3chapter imp questions for chemistry 🧪🙀

 🔬 Chapter 1: Some Basic Concepts of Chemistry

🔸 Important Questions:

1. Define mole. How is it related to Avogadro’s number?

2. What is the law of conservation of mass? Give one example.

3. Differentiate between empirical and molecular formula with examples.

4. Calculate the molar mass of the following compounds:

a) H₂SO₄

b) CaCO₃

5. A compound contains 40% C, 6.7% H, and 53.3% O. Find its empirical formula.

6. Define limiting reagent. How does it affect the amount of product formed?

7. What do you understand by stoichiometry? Give an example.

8. What is the difference between atomic mass and molar mass?

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⚗️ Chapter 2: Structure of Atom

🔸 Important Questions:

1. State the main postulates of Bohr’s model of an atom.

2. What are the limitations of Rutherford’s model?

3. Define isotopes, isobars, and isotones with examples.

4. Calculate the wavelength of light emitted when an electron in a hydrogen atom jumps from n = 4 to n = 2.

5. Explain the terms:

a) Quantum numbers

b) Orbitals

6. Derive the relationship between wavelength and frequency.

7. Write the electronic configuration of the following:

a) Fe

b) Cl⁻

c) Cu⁺

8. What is the Heisenberg Uncertainty Principle? Explain with a formula.

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🧪 Chapter 3: Classification of Elements and Periodicity in Properties

🔸 Important Questions:

1. State Modern Periodic Law. How does it differ from Mendeleev’s Periodic Law?

2. Define the following periodic properties:

a) Atomic radius

b) Ionization enthalpy

c) Electron affinity

d) Electronegativity

3. How do ionization enthalpy and atomic size vary across a period and down a group?

4. Why are noble gases placed in group 18?

5. Explain why the first ionization energy of Mg is greater than that of Al.

6. Define effective nuclear charge. How does it affect atomic size?

7. Arrange the following in increasing order of atomic radius:

N, O, F, C, B

8. What are the causes of periodicity in the properties of elements?

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