WAEC Past Questions and Answers - Page 4187

Which of the following statements about the atom is/are correct?

I. Energy is needed to remove electrons from an atom
II. Particles in the nucleus of an atom are bound together by strong forces.
III. A large amount of energy is required to separate the particles in the nucleus of an atom.
IV. When the nucleus of a uranium atom is split, the energy released accounts for the difference in the masses of the products and the parent nucleus

When the pressure of the gas in a discharge tube is gradually lowered.

I. there is a violet glow in the tube
II. the glow in the tube splits into bands which get further apart.
III, the glow and the bands eventually disappear and there is a green fluorescence in the tube. IV. the tube breaks into pieces.

Which of the following are correct?

Which of the following particles conduct electricity through salty water?

Which of the following reduce(s) the effect of the back e.m.f. generated in the primary coil of an induction coil?

I. The capacitor in the circuit
II. The make and break contact in the circuit
III. The ratio of turns in the secondary to that in the primary

How long will it take to heat 3 kg of water from 28^oC to 88^oC in an electric taking a current of 6 A from an e.m.f. source of 220V?