Air, Water and Climate

Question 1

composition of clean, dry air

Answer 1

78% nitrogen
21% oxygen
1% noble gases (argon)

Question 2

source and effects of carbon dioxide

Answer 2

• source: complete combustion of carbon-containing fuels
• effects: global warming and climate change

Question 3

source and effects of carbon monoxide

Answer 3

• source: incomplete combustion of carbon-containing fuels
• effects: toxic gas

Question 4

source and effects of particulates

Answer 4

• source: incomplete combustion of carbon-containing fuels
• effects: risk of respiratory problems and cancer

Question 5

source and effects of methane

Answer 5

• source: decomposition of vegetation and waste gases from animal digestion
• effects: global warming and climate change

Question 6

source and effects of oxides of nitrogen

Answer 6

• source: reacts with oxygen in high temp. in car engines
• effects: acid rain, photochemical smog and respiratory problems

Question 7

source and effects of sulfur dioxide

Answer 7

• source: combustion of sulfur-containing compounds
• effects: acid rain

Question 8

strategies to reduce climate change

Answer 8

planting trees
reduction of livestock farming
decreasing use of fossil fuels
increasing use of renewable energy and hydrogen

Question 9

strategies to reduce acid rain

Answer 9

catalytic converters
low-sulfur fuel
flue gas desulfurisation with calcium oxide

Question 10

greenhouse gases and global warming

Answer 10

• sun emits thermal energy
• it is absorbed by molecules of Earth’s surface (changes it into thermal energy and surface becomes warmer)
• some light is reflected by Earth and is trapped by greenhouse gases
• as molecules cool, if they point away from the earth, thermal energy is lost, cooling them down (lost to space)

Question 11

photosynthesis

Answer 11

reaction between CO2 and water to produce glucose and oxygen in the presence of chlorophyll and using energy from light

Question 12

chemical tests for presence of water

Answer 12

anhydrous copper (ii) sulfate
anhydrous cobalt (ii) sulfate

Question 13

anhydrous copper (ii) sulfate

Answer 13

• positive: blue
• negative: white

white –> blue

Question 14

anhydrous cobalt (ii) chloride

Answer 14

• positive: pink
• negative: blue

blue –> pink

Question 15

test for purity of water

Answer 15

• boils at 100
• freezes at 0

Question 16

why is distilled water used in practicals

Answer 16

it has less chemical impurities

Question 17

impurities on water

Answer 17

• dissolved oxygen
• metal compounds
• plastics
• sewage
• harmful microbes
• nitrates from fertilisers
• phosphates from fertilisers and detergents

Question 18

dissolves oxygen

Answer 18

good
for aquatic life

Question 19

metal compounds

Answer 19

provides minerals
(can be toxic)

Question 20

plastics

Answer 20

harm aquatic life

Question 21

sewage

Answer 21

has harmful microbes which cause disease

Question 22

harmful microbes

Answer 22

harmful

Question 23

nitrates from fertilisers

Answer 23

lead to water deoxygenation
harms aquatic life

Question 24

phosphates from fertilisers and detergents

Answer 24

lead to water deoxygenation
harms aquatic life

Question 25

sedimentation tanks

Answer 25

water stays still so insoluble heavy solids fall to the bottom

Question 26

filtration

Answer 26

water flows to smaller and smaller sized sand particles which remove small insoluble solid impurities

Question 27

carbon particles

Answer 27

water pushed through carbon particles with very high surface area
removes any molecule that gives water unusual taste/smell

Question 28

chlorination

Answer 28

chlorine gas bubbles into water
kills bacteria and destroys viruses