P2.6

Question 1

What does nuclear fission produce?

Answer 1

Heat, which is used to generate electricity

Question 2

What main substances are used in nuclear fission?

Answer 2

~ Uranium235

~ Plutonium239

Question 3

How do nuclear power stations work?

Answer 3

~ Fuel rods of uranium235 or plutonium239 make heat 
~ Heat warms the water
~ Produces steam 
~ Turns turbines 
~ Generates electricity

Question 4

What happens when a neutron is fired into a nucleus?

Answer 4

~ The nucleus splits into 2 nuclei

~ 2 or 3 more neutrons are released

Question 5

What is a chain reaction?

Answer 5

When neutrons produced from the splitting of a nuclei hit into more nuclei and the chain continues

Question 6

How is nuclear fission controlled so it doesn’t continue forever?

Answer 6

Some substances can be used to absorb the neutrons

Question 7

What is nuclear fusion?

Answer 7

When the nucleus of one atom joins with the nucleus of another atom

Question 8

What is the problem with nuclear fusion?

Answer 8

Each nucleus has a positive charge so they strongly repel and it’s difficult to get them to fuse

Question 9

Where does nuclear fusion happen?

Answer 9

In the centre of stars

Question 10

What gases make up the sun?

Answer 10

75% hydrogen

25% helium

Question 11

What makes nuclei fuse?

Answer 11

~ Heat

~ Gravitational force

Question 12

When 2 hydrogen nuclei fuse what do they form?

Answer 12

Helium nucleus

Question 13

Why should energy from nuclear fission be used in power stations?

Answer 13

~ Not radioactive

~ Better byproduct for the environment

Question 14

What is one disadvantage of nuclear fusion?

Answer 14

High temperatures required

Question 15

What is a disadvantage of nuclear fission?

Answer 15

Produces radioactive waste

Question 16

What were the first two elements produced 100,000 years after the Big Bang?

Answer 16

Hydrogen and helium

Question 17

What is a protostar?

Answer 17

A cloud of hydrogen and helium

Question 18

What force acts as hydrogen and helium get closer together?

Answer 18

Gravity

Question 19

What happens when gravity increases in a protostar?

Answer 19

The hydrogen fuse together

Question 20

In a main sequence star the gravity is equal to what?

Answer 20

The force caused by nuclear radiation

Question 21

What happens to a main sequence star after billions of years?

Answer 21

~ It runs out of hydrogen and the fusion reactions decrease

~ Star becomes a red giant

Question 22

Why does a red giant star shrink to a white dwarf star?

Answer 22

Because it runs out of fuel

Question 23

What happens to stars about the size of the sun at the end of their life?

Answer 23

~ It will expand and become a red giant
~ Red giant cools and collapses under its own gravity to become a white dwarf
~ White dwarf slowly cools to become a black dwarf

Question 24

What happens to stars larger than the sun at the end of their life?

Answer 24

~ Expand to become red supergiants
~ Shrinks and explodes which releases lots of energy, dust and gas into space (supernova)
~ Remains may form a neutron star, some of these collapse to form black holes

Question 25

What element is produced in the centre of stars?

Answer 25

Iron

Question 26

What elements are produced from a supernova?

Answer 26

Elements heavier than iron

Question 27

What is a black hole?

Answer 27

A very dense body which attracts everything and doesn’t let anything escape, even light

Question 28

What is the solar system believed to have formed from?

Answer 28

Material produced when earlier stars exploded

Question 29

What must happen before nuclear fission can happen?

Answer 29

The uranium235 or plutonium239 must absorb a neutron

Question 30

How do stars form?

Answer 30

Dust and gas from space is pulled together by gravitational attraction

Question 31

How do planets form?

Answer 31

From smaller masses being attracted by a larger mass

Question 32

How have all of the naturally occurring elements been produced?

Answer 32

Through fusion processes in stars