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structured questions Flashcards

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1
Q

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

A

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

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2
Q

why are the elements in group 0 inert?

A

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

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3
Q

what are the 2 main elements present in a petroleum fraction

A

carbon and hydrogen

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4
Q

what happens to the particles when solid is heated

A

they gain energy and move further apart

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5
Q

arrangement of particles during condensation

A

particles become closer together and move more easily

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6
Q

particles - evaporation of water

A

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

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7
Q

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

A

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

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8
Q

what are the 3 ways to test the purity

A

boiling point
melting point
paper chromatography

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9
Q

define diatomic

A

refers to two atoms chemically bonded together to form a molecule

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10
Q

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

A

steam to ice

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11
Q

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

A

OH-n (aq) + H+ (aq) —–> H2O (l)

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12
Q

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

A

oxygen in the test tube is used up during rusting

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13
Q

state a method by which the precipitate can e separated

A

filtration

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14
Q

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

A

as it can only measure up to 0.5cm3

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15
Q

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

A
  1. they are soft and cut easily with a knife
  2. low densities
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16
Q

which 3 metals are unreactive to acid

A

copper
silver
gold

17
Q

explain why carbon monoxide is formed in car engine

A

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

18
Q

explain why cracking method is important in oil industry

A

to produce smaller and more useful molecules

19
Q

describe how fractional distillation separates paraffin from petroleum

A

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

20
Q

state how nitrogen dioxide acts as an atmospheric pollutant

A

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

21
Q

what is a poisonous gas

A

carbon monoxide

22
Q

which gas is colourless and odourless

A

carbon monoxide

23
Q

do u have to put the Mr units?

A

no need

24
Q

what is the physical state of glucose in room temperature

A

solid

25
Q

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

A

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

26
Q

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

A

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

27
Q

what are the advantages of recycling metal

A

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

28
Q

why recycle metal

A

as metals are in high demand as they are limited resources

29
Q

define alloy

A

is a mixture of metals with other elements

30
Q

fractional column use for

A

to separate the liquids

31
Q

ammonium hydroxide

A

NH4OH

32
Q

brass is made up of

A

copper and zinc

33
Q

bronze is made up of

A

copper and tin

34
Q

steel is made up of

A

iron and carbon

35
Q

stainless steel is made up of

A

iron and carbon and chromium

36
Q

cations

A

metals from positively charged ions

37
Q

anions

A

non metals from negatively charged ions

38
Q

glass beads

A

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

z-chemistry (15 decks)

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