JAMB Physics Past Questions & Answers - Page 228

Which of the following statements describes an atom accurately?

i. atoms of all elements are identical
ii. an atom contains a nucleus and number of electrons
iii. due to the electrons in the atom an atom is negatively charged
iv. electrons in the atom move in circular orbits round the nucleus

A small steel needle is carefully floated on water in a beaker. When a few drops of kerosine are introduced into the water the needle sink.

Which of the following statements correctly explain(s) the observation?

i. there is tension on the water surface
ii. kerosine reduces the density of water so that needle becomes denser than water
iii. kerosine reduces the surface tension of water

A body of mass 5kg initially at rest is acted upon by two mutually perpendicular forces 12N and 5N as shown in fig.3. If the particle moves in the direction QA, calculate the magnitude of the acceleration

A plane inclined at an angle of 30^o to the horizontal has an efficiency of 60%. The force parallel to the plane required to push a load of 120N uniformly up the plane is

If a solid changes directly into a gas when heat is applied the process is called