structured questions

Question 1

why does molten ___ (e.g. iron) do not react with the incoming air

Answer 1

as hot air rises, it will not come in contact with the heavy molten iron which will sink to the bottom

Question 2

why are the elements in group 0 inert?

Answer 2

it has a full valence shell that does not want to lose or gain electrons hence it is not reactive

Question 3

what are the 2 main elements present in a petroleum fraction

Answer 3

carbon and hydrogen

Question 4

what happens to the particles when solid is heated

Answer 4

they gain energy and move further apart

Question 5

arrangement of particles during condensation

Answer 5

particles become closer together and move more easily

Question 6

particles - evaporation of water

Answer 6

particles move further apart
orderliness of particles in both water and water vapour remains unchanged

Question 7

why farmers should not add excessive amount of calcium oxide to soil

Answer 7

the soil will become too alkaline and will not be suitable for plant growth

Question 8

what are the 3 ways to test the purity

Answer 8

boiling point
melting point
paper chromatography

Question 9

define diatomic

Answer 9

refers to two atoms chemically bonded together to form a molecule

Question 10

in which conversion do water molecules lose speed
ice to steam or steam to ice

Answer 10

steam to ice

Question 11

write an ionic equation to show what it meant by the term neutralisation

Answer 11

OH-n (aq) + H+ (aq) —–> H2O (l)

Question 12

explain why the water level in the test tube has risen after one week

Answer 12

oxygen in the test tube is used up during rusting

Question 13

state a method by which the precipitate can e separated

Answer 13

filtration

Question 14

explain why a measuring cylinder is not suitable for making this measurement

Answer 14

as it can only measure up to 0.5cm3

Question 15

state two physical properties of sodium that are typical of group 1

Answer 15

1. they are soft and cut easily with a knife
2. low densities

Question 16

which 3 metals are unreactive to acid

Answer 16

copper
silver
gold

Question 17

explain why carbon monoxide is formed in car engine

Answer 17

it is produced by the incomplete combustion of fossil fuels in the car engines

Question 18

explain why cracking method is important in oil industry

Answer 18

to produce smaller and more useful molecules

Question 19

describe how fractional distillation separates paraffin from petroleum

Answer 19

fractional distillation
petroleum is heated in a furnace into a vapour
it then rise up in the column and begins to cool and condense
fractions with smaller hydrocarbons have lower boiling points, cools and condenses first
collected at the top

Question 20

state how nitrogen dioxide acts as an atmospheric pollutant

Answer 20

acidic oxide dissolve in water to produce acid rain
killing aquatic life

Question 21

what is a poisonous gas

Answer 21

carbon monoxide

Question 22

which gas is colourless and odourless

Answer 22

carbon monoxide

Question 23

do u have to put the Mr units?

Answer 23

no need

Question 24

what is the physical state of glucose in room temperature

Answer 24

solid

Question 25

explain why is it a good practise to repeat titration several times

Answer 25

to ensure that consistent readings are obtained so that the result will be reliable

Question 26

describe a test that could be carried out on the soil sample to show that the soil had changed from acidic to alkaline

Answer 26

add universal indicator
observation before: acidic soil will turn universal indicator orange/ yellow
observation after: alkaline soil will turn universal indicator blue

Question 27

what are the advantages of recycling metal

Answer 27

to reduce the usage of landfills
conserve earth’s finite natural resources

Question 28

why recycle metal

Answer 28

as metals are in high demand as they are limited resources

Question 29

define alloy

Answer 29

is a mixture of metals with other elements

Question 30

fractional column use for

Answer 30

to separate the liquids

Question 31

ammonium hydroxide

Answer 31

NH4OH

Question 32

brass is made up of

Answer 32

copper and zinc

Question 33

bronze is made up of

Answer 33

copper and tin

Question 34

steel is made up of

Answer 34

iron and carbon

Question 35

stainless steel is made up of

Answer 35

iron and carbon and chromium

Question 36

cations

Answer 36

metals from positively charged ions

Question 37

anions

Answer 37

non metals from negatively charged ions

Question 38

glass beads

Answer 38

provide large surface area so that vapour can undergo repeated condensation and boiling