Question 4376:

• NECO 2001

The magnetic effect of a current-carrying coil is NOT utilized in the making of a/an ____________

A. Carbon microphone
B. Electric bells
C. Magnetic relay
D. Telephone earpiece
E. Thermostat

Question 4377:

• NECO 2001

In 24 days a radioactive isotope decreases in mass from 128g to 2g. What is the half-life of the radioactive material?

A. 2.54 days
B. 4.00 days
C. 4.80 days
D. 6.00 days
E. 8.00 days

Question 4378:

• NECO 2001

The invisible part of the spectrum of white light consists of ____________

A. Infra-red and ultra-violet only
B. Infra-red, ultra-violet and blue only
C. Red, orange and green only
D. Red and violet only
E. Yellow and indigo only

Question 4379:

• NECO 2001

50cm³ of air at a pressure of 5Nm^-2 is enclosed in a metal tube by a piston. If the piston is pushed in a distance of 10cm, what will the pressure of the air become, if the cross-sectional area of the tube is 2cm^-2? (Assume that the temperature remains constant throughout)

A. 12.5 Nm^-2
B. 8.7 Nm^-2
C. 8.3 Nm^-2
D. 3.8Nm^-2
E. 3.0Nm^-2

Question 4380:

• NECO 2001

Which scientist discovered natural radioactivity?

A. Enrico Fermi
B. Henri Becquerel
C. Marie Curie
D. Micheal Faraday
E. Niels Bohr