Atoms

Q. Who is the first person to propose the concept of an atom ?

1. Democritus
2. John Dalton
3. Ernst Rutherford
4. J.J. Thomson

Q. The word atom comes from the Greek word 'atomos' which means uncuttable.

1. False
2. True

Q. Prior to the experiments with cathode tubes, the smallest particles that make up the matter was believed to be ______ .

1. electrons
2. atoms
3. protons
4. molecules

Q. Analyse the following statements and choose the correct option.

(i) Melamine is a plastic commonly used in kitchenware
(ii) Melamine is a cross-linked polymer just like bakelite
(iii) The effect of heat on melamine is the same as that on PET plastic
(iv) Melamine and Bakelite are good conductors of heat and electricity

1. (i), (ii) and (iv)
2. (i) and (ii)
3. (ii), (iii) and (iv)
4. (i) and (iii)

Q. In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g of water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass.
Sodium carbonate + Ethanoic acid → Sodium ethanoate + Carbon dioxide + Water

[2 Marks]

Q. Which of the following elements has its symbol given in the correct format?

1. Aluminium - Al
2. Zinc - ZN
3. Fluorine - f
4. Boron - B

Q.

__ is the international organization who approves names of elements. (Write only the abbreviation)

Q.

If we rub a comb in dry hair, then this comb attracts small pieces of paper. Which of the following can relate to this?

1. Atoms are indivisible

2. Atoms repel each other

3. Atoms can attract each other

4. Atoms are divisible

Q. Protons, neutrons and electrons together constitute an atom.

1. False
2. True

Q.

Which of the following molecules is made up of different kinds of atoms?

1. Water molecule

2. Oxygen molecule

3. Hydrogen molecule

4. Nitrogen molecule