practice questions

Question 1

Beta decay does not cause the mass number of an atom to change. Explain why not.

Answer 1

A neutron turns into a proton

Question 2

It is impossible for the alpha decay of bismuth-212 to produce the same element as the beta decay of bismuth-212. Explain why.

Answer 2

• The number of protons determines the element
• Alpha and beta decay produce different changes to the number of protons

Question 3

explain why having a more efficient motor increases the top speed of the car

Answer 3

• higher proportion of energy is transferred to the kinetic energy store of the car
• lower proportion of wasted energy

Question 4

describe the movement of the particles of helium gas inside the ballon

Answer 4

• range of speeds
• moving in different directions

Question 5

explain what led to the plum pudding model of the atom being replaced by the nuclear model of the atom

Answer 5

• alpha particle scattering experiment
• alpha particles directed at gold foil
• most alpha particles pass straight through
• (so) most of atom is empty space
• a few alpha particles deflected through large angles
• (so) mass is concentrated at centre of atom
• (and) nucleus is (positively) charged
• plum pudding model has mass spread throughout atom
• plum pudding model has charge spread throughout atom

Question 6

describe the process of nuclear fission inside a nuclear reactor

Answer 6

• neutron absorbed by uranium nucleus
• nucleus splits into two smaller nuclei
• two or three neutrons are released
• and gamma rays are emitted

Question 7

what happens when you rub a polythene rod with a dry cloth?

Answer 7

• electrons are transferred to the surface of the rod from the cloth
• the rod becomes negatively charged

Question 8

what happens when you rub a perspex rod with a dry cloth?

Answer 8

• electrons are transferred from the surface atoms of the rod on to the cloth
• the rod becomes positively charged

Question 9

explain how the process of nuclear fission leads to the release of energy

Answer 9

• lighter nuclei join to form heavier nuclei
• some of the mass of the nuclei is converted to energy of radiation

Question 10

explain the advantage of the radioactive waste having a shorter half-life

Answer 10

• activity decreases quickly
• risk of harm decreases quickly

Question 11

explain why adding resistors in parallel decreases the total resistance

Answer 11

• multiple paths for charge to flow
• total current is greater for the same potential difference when more resistors are added

Question 12

explain why the pressure exerted by the helium inside the ballon would increase if the temperature increased but the mass and volume remained constant

Answer 12

• the particles would have a higher mean kinetic energy
• so increased number of collisions with the walls of the balloon per second
• greater forces exerted in collisions
• greater force exerted on the same area

Question 13

what is sublimation?

Answer 13

when a solid changes into a gas, without passing though the liquid state

Question 14

describe how the student could measure the volume of the piece of rock

Answer 14

• partly fill a measuring cylinder with water
• measure the initial volume
• place the rock into the water
• measure the final volume
• volume of the rock equals the final volume subtract the initial volume

Question 15

why is a wire called an ohmic conductor?

Answer 15

• the resistance stays constant as the current changes
• provided its temperature stays constant

Question 16

explain how the resistance of a filament lamp changes when the current through the filament is increased

Answer 16

• resistance increases as current increases
• because the temperature of the bulb increases
• so metal ions in the filament lamp vibrate more and resist passage of electrons through filament more