Rocks

Question 1

(1) What is formed from limestone when it is subjected to heat and pressure?

Answer 1

Metamorphic Rocks

Question 2

(2) Give an advantage and a disadvantage, to local communities, of a nearby limestone
quarry

Answer 2

advantage
(brings in) money / employment (1)
disadvantage
dust / noise pollution /extra traffic
/destroys (wildlife) habitat /damages
landscape /damages natural beauty
/ less tourists (1)

Question 3

(3) Limestone is a natural form of calcium carbonate.
Limewater is calcium hydroxide solution.
Describe how limewater can be made from calcium carbonate.

Answer 3

heat/thermally decompose
(calcium carbonate)(1)
• to form calcium oxide (1)
• {react (calcium oxide) with /
add} water (1)
• to form (solid) calcium
hydroxide (1)
• add (more) water / dissolve
(calcium hydroxide) in water
(1)
• filter (1)

Question 4

(6) The limestone shown in the photograph was originally formed beneath the sea and
then earth movements forced the rock upwards to form the cliff.
Describe how the limestone was originally formed and has become the cliff face
shown in the photograph.

Answer 4

formed from sediments / shells
• sediments fall to the bottom of the sea
• layers of sediment build up on top of one another
• over (very) long time period
• rock formed / compaction
• (caused by)pressure (from the layers above and minerals)
• (cause) the sediment to ‘stick together’
• (to form)layers
• rock movement/change in sea level
• (more recently) rock has been weathered / eroded (by sea)
• because it is a soft rock

Question 5

(1) State what type of rock limestone is.

Answer 5

sedimentary

Question 6

(2) Explain how the marble has formed above the granite.

Answer 6

limestone (1)
• (changed by) heat (1)
• (changed by) pressure (1)
• (heat from) magma / {hot
/ molten} rock (next to it)
(1)

Question 7

(2) explain why the rock at X contained larger crystals than the rock at Y

Answer 7

X cools slowly (1)
• Y cools quickly (1)
• suggested reason for
slower cooling e.g. larger
volume (of rock) / further
below surface / heat
escapes more slowly
/further from edge of
molten rock (1)

Question 8

(1) CaCO3 → CaO + ………………………….

Answer 8

CO2

Question 9

(2) Calcium oxide reacts with water to form calcium hydroxide.
Write the balanced equation for this reaction.

Answer 9

CaO + H2O → Ca(H0)2

Question 10

(2) Explain why calcium hydroxide (slaked lime) is spread on fields

Answer 10

(calcium hydroxide) alkaline / base
/ alkali (1)
• neutralises / neutralisation (1)
• (applied to) acid(ic) (soil) (1)

Question 11

(2) Suggest how you could show that, when calcium carbonate is heated, a
reaction takes place.

Answer 11

ther
• {find mass of / weigh} solid before
heating (1)
• (heat in a suitable container) and
{find mass / weigh} again (when
cool) (1)

Question 12

(2) Describe what you would observe when water is added, one drop at a time, to
cold calcium oxide

Answer 12

fizzing / hissing (1)
• steam (1)
• swells (1)
• solid crumbles (to a powder) (1)
• becomes hot (1)

Question 13

(2) Write the balanced equation for the reaction of calcium hydroxide with
carbon dioxide

Answer 13

Ca(OH)2 + CO2 → CaCO3 + H2O

Question 14

(1) State the common name for calcium hydroxide solution.

Answer 14

limewater

Question 15

(2) Explain why calcium carbonate removes acidic gases from emissions in power
station chimneys.

Answer 15

(calcium carbonate) reacts with
{acidic gases / sulphur dioxide} (1)
• (because) calcium carbonate is a
base (1)
• to form a salt / calcium sulfate (1)
• neutralisation (reaction) (1)

Question 16

(1) Which of the following is a rock that is another form of calcium carbonate?

Answer 16

chalk

Question 17

(2) It is possible that not all of the calcium carbonate decomposed when it was
heated.
Suggest what could be done to confirm that the decomposition was complete

Answer 17

heat remaining solid/ heat it for
longer / heat it again (1)
mass after heating stays the
same / gas does not turn
limewater milky (1)
or
add acid (1)
no effervescence (1)

Question 18

(2) Calcium oxide reacts with water to form calcium hydroxide.
Write the balanced equation for this reaction.

Answer 18

CaO + H2O → Ca(OH)2

Question 19

(2) Calcium carbonate is used to treat waste gases produced in coal-fired power
stations.
Explain why calcium carbonate is used in this way

Answer 19

{neutralises / reacts with /
removes / destroys/ gets rid of /
takes in} the (waste) gases(1)
acid(ic) (gases) / carbon dioxide
/ sulfur dioxide / oxides of
nitrogen (1)

Question 20

(1) An example of a metamorphic rock is

Answer 20

marble

Question 21

(3) Explain how these igneous rocks, containing different sized crystals, have been
formed.

Answer 21

magma/lava/molten rock
(1) M1
• cools (1) M2
• (A cools) quickly to form
small crystals (1) M3
• (B cools) slowly to form
large crystals(1) M4

Question 22

(3) Explain why calcium carbonate is used to treat waste gases produced in coal-fired
power stations

Answer 22

(waste) gases acidic (1)
M1
• calcium carbonate basic
(1) M2
• (calcium carbonate) reacts
with/neutralises/forms
(correctly named) salt with
(waste acidic gases) (1)
M3
• coal contains sulfur
(impurity) (1) M4
• (burns to form) sulfur
dioxide (1) M5
• sulfur dioxide causes acid
rain M6
• (calcium carbonate)
reduces acid rain (1) M7