Q4. (i) Name an element that does not contain a neutron.

(ii) If an atom contains one electron and one proton, will it carry any charge or not?

Q5. On the basis of Thomson’s model of an atom, explain how an atom as a whole is neutral.

Q6. How is it shown that an atom has a tiny space at its center?

Q7. What information is conveyed by this statement: Sodium atom has a large empty space or large nuclear space?

Q8. (i) From the symbol \(_{12}^{24}\text{Mg}\), state the mass number and electronic configuration of magnesium.

(ii) How many protons and neutrons are present in magnesium?

Q9. Element X has electronic configuration 2, 8, 8, 1.

• (i) Predict its charge and write the symbol for ion X.
• (ii) Write whether X will be an oxidizing agent or reducing agent. Why?

Q10. Define the term “isotope.”

Q11. An ion carries a positive charge by losing one electron. Write the number of protons and electrons in this ion.

Q12. With reference to which fundamental particle do isotopes differ? Give two uses of isotopes.

Q13. Why do \(_{17}^{35}\text{Cl}\) and \(_{17}^{37}\text{Cl}\) have the same chemical properties? In what respect do these atoms differ?

Q14. Explain fractional mass. What is the fractional mass of chlorine?

Q15. Write down the electronic configuration of:

• (i) Chlorine
• (ii) Chloride ion (Cl⁻)

Q16. Explain the octet rule for the formation of sodium chloride.

Q17. Name the ion formed when an atom of chlorine gains one electron. What is the change in the number of protons and electrons?

Q18. (i) What is the oxidation number of nitrogen in ammonia and ammonium molecule?

(ii) What is the molecular formula of ammonium ion?

(iii) Name the covalent bond in ammonium chloride.

Q1. State Dalton’s atomic theory.

Q2. Which subatomic particle was discovered by:

• (i) Chadwick?
• (ii) Thomson?
• (iii) Goldstein?

Q3. Name the subatomic particle whose charge is:

• (i) +1
• (ii) -1
• (iii) 0

Q4. Which metal did Rutherford select for his alpha-particle scattering experiment and why?

Q5. (i) What is the symbol and charge of the following fundamental particles?

• (a) Electron
• (b) Proton
• (c) Neutron

(ii) Give the symbol of each particle and their relative charge.

Q6. (i) Name X and label the charge on it.

(ii) Draw Bohr’s model of an atom with labels A, B, and C.