1 Mark Questions

Q1. Fill in the blanks with the correct choice given in brackets.

• (i) If an element has two electrons in its outermost shell, then it is likely to be a _____ [Metallic / Non-metallic].
• (ii) Give the first scientific theory about the structure of matter. [Goldstein / John Dalton]
• (iii) The magnitude of negative charge carried by electrons is _____. [1.6 × 10⁻¹⁹ C / 1.6 × 10¹⁹ C]
• (iv) Bombarding beryllium atom with alpha particles results in the formation of carbon isotope and _____. [Proton / Neutron]
• (v) The maximum number of electrons in L shell is _____. [8 / 18]
• (vi) The three isotopes of hydrogen are _____. [Protium / Tritium / Deuterium]

Q2. Choose the correct options.

• (i) Rutherford’s alpha-particle scattering experiment shows that:
• a) Electrons revolve
• b) Proton
• c) Atomic nucleus
• d) Number of valence electrons
• (ii) The number of valence electrons in O²⁻ is:
• a) 6
• b) 8
• c) 2
• d) 4
• (iii) Which of the following is the correct electronic configuration of potassium?
• a) 2, 8, 8, 1
• b) 2, 8, 1
• c) 2, 1
• d) 2, 8, 7
• (iv) Who is given the credit for the discovery of electrons?
• a) William Crookes
• b) J.J. Thomson
• c) Goldstein
• d) Rutherford
• (v) Identify the pair of isotopes:
• a) 40Ar and 39K
• b) 40Ar and 40K
• c) 12C and 14C
• d) 30P and 30Si
• (vi) The electronic configuration of magnesium is:
• a) 2, 8, 2
• b) 2, 8, 3
• c) 2, 8, 4
• d) 2, 8

Q3. What is an alpha (α) particle?

Q4. What is the nature of charge on cathode rays and anode rays?

Q5. How are X-rays produced?

Q6. State one observation that shows that an atom is not indivisible.

Q7. On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?

Q8. Name the fundamental particle discovered by Chadwick.

Q9. State the major drawback of Rutherford’s model of an atom.

Q10. What is the significance of the number of protons found in the atoms of different elements?

Q11. Define the term “isobars.”

Q12. From the symbol \( _{6}^{12} \text{C} \), write down the mass number and atomic number.

Q13. What is meant by the term “electronic configuration”?

Q14. Ionic compounds have high melting and boiling points. Explain.

Q15. Name the following:

• (i) Anions
• (ii) Cations
• (iii) Neutrons

Q16. Draw the orbit diagram for helium atom.

Q17. Identify the missing element and complete the following equation:

\( \text{Be} + ? \rightarrow _{6}^{12} \text{C} + _{2}^{4} \text{He} \)

Q18. What is the missing element in the reaction:

\( ^{14}_{6} \text{C} \rightarrow ^{14}_{7} \text{N} + ? \)