A. Fill in the blanks.
1. The nucleus consists of ———————and ————————
2. The model which resembled the solar system was proposed by——
3. Anode rays travel towards——————————
4. An electron has ——————— charge.

B. Classify the following statements as true or false.
1. The plum pudding model was proposed by Rutherford.
2. Cathode is the negatively charged electrode.
3. Neutrons are constituents of atoms of all elements.
4. The number of electrons present in a neutral atom is always equal to the number of protons.

C. Multiple choice type questions.

1. An a-particle has
(a) 2 protons only. (b) 2 neutrons only
(c) 2 protons and 2 neutrons (d) 2 neutrons

2. Isotopes have
(a) same mass number (b) same atomic number
(c) different atomic number (d) same mass as well as atomic number

3. The mass of a neutron
(a) is less than that of a proton. (b) is greater than that of a proton.
(c) is equal to that of a proton. (d) zero

4. The filling of second shell starts with
(a) He (b) Li
(c) C (d) N

5. The electronic configuration of Cl is
(a) 2, 8 (b) 2, 8, 4
(c) 2, 8, 6 (d) 2, 8, 7

6. Which of the following elements has completely filled shells?
(a) H (b) O
(c) Ne (d) Mg

D. Descriptive type questions.

1. How can you say that electrons are present in all types of matter?
2. Define an orbit.
3. Calculate the number of neutrons present in ¹⁶₈O and ¹⁹₉F
4. The mass number of iron is 56. If 30 neutrons present in its atom, what is its atomic number?
5. Which of the following are isotopes? ¹²₆C, ¹⁴₆C, ¹⁴₇N