# data[].attributes.body
it is a good conductor of electricity
it has high melting pot boiling point

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Good conductor of electricity.It has a high melting point

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It is soluble
The melting point is very high

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Good conductor of electricity
High milting and boiling point

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(a)It has a high melting and boiling point; it can conduct electricity in the molten or aqueous state

# data[].attributes.body
It has highmelting and boiling point.
It can conduct electricity in molten or aqueous solution.

# data[].attributes.body
it is good conductor of electricity
It has high melting and boiling point ‘

# data[].attributes.body
weifeng
the magnesium atoms lose two electrons to form magnesium ion the sulfur atoms gain two electrons to form sulfur ion

# data[].attributes.body
It has high melting point.It is a good conductor of electricity.

# data[].attributes.body
It has a high melting point and is an good electrical conductor

# data[].attributes.body
Magnesium ion will lose 2 electron atom to sulfur and sulfur atom gain 2 electron To form magnesium sulfide

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The bonding is ionic bonding.Magnesium atom transfer its valence electrons to the sulfide ions

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Good conductor of electricity
High mp and bp

# data[].attributes.body
The metal electron, magnesium, transfers its electron to the non-metal, sulfur atom, forming an ionic compound.
Magnesium lose electrons to form positive ions while sulfur gains electrons to form negative ions.

# data[].attributes.body
Magnesium atom gives two electrons to sulfur atom to form an ionic compound.Hence magnesium loses electrons becomes to magnesium ion, sulfur atom gains electrons becomes a sulfide ion.

# data[].attributes.body
weifeng

the magnesium atoms lose two electrons to form magnesium ion the sulfur atoms gain two electrons to form sulfur ion

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b)Magnesium atom gives two electrons to sulfur atom to form a magnesium ion, sulfur atom receive two electrons from magnesium atom to form a sulfur ion.

# data[].attributes.body
white precipitate of barium sulfate
white precipitate of calcium carbonate
no precipitate

# data[].attributes.body
It has a high melting point and is an good electrical conductor

# data[].attributes.body
It is a good conductor of electricity
It has a high melting point

# data[].attributes.body
weifeng
white ppt of Ba S O4
white ppt of CaCO3
no ppt

# data[].attributes.body
White precipitate of barium sulfate
White precipitate of calcium carbonate
No precipitate

# data[].attributes.body
Magnesium losses two electrons in order to form a magnesium ion and sulfur atom gets the ions from Mg to form nagetive sulfur ion.

# data[].attributes.body
Han Yining

Magnesium atom loss two electrons to sulfur atom to form magnesium ion, sulfur atom  gain two electrons from magnesium atom to from a sulfur ion.

# data[].attributes.body
Magnesium loses two electrons and transfers two electrons to sulfur

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I)It is to obtain the precipitate formed,which is lead (ll)bromide
II)It is to remove any potassium nitrate present.

# data[].attributes.body
1.white precipitate of barium sulfate
2.white precipitate of calcium carbonate
3.no precipitate

# data[].attributes.body
White precipitate of barium sulfate
White precipitate of calcium carbonate
No precipitate

# data[].attributes.body
Magnesium lose two electrons transfer to sulfur  and become magnesium ion ,sulfur gains two electrons becomes sulfide ion

# data[].attributes.body
White precipitate of Barium sulfate
White precipitate of Calcium carbonate
No precipitate

# data[].attributes.body
White precipitate of barium sulfate
White precipitate of calcium carbonate
No precipitate

# data[].attributes.body
White precipitate of barium sulfate
White  precipitateof barium carbonate
NO ppt

# data[].attributes.body
white ppt of barium sulfate
white ppt of calcium carbonate
no ppt

# data[].attributes.body
Han Yining

White precipitate of barium sulfate.
White precipitate of barium carbonate.
No precipitate

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weifeng
to  separate the residue and filtrate and to filter off the residue

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to wash off the impurties on the residue and to get pure lead bromide

# data[].attributes.body
White precipitate of Barium sulfate is formed
White precipitate of calcium carbonate is formed
No precipitate

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(I) It is used to remove excess water,
(II)It is used to get pure substance

# data[].attributes.body
White ppt of BaSO4    White ppt of CaCO3  no ppt

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Add a few drops of aqueous sodium hydroxide to aqueous ammonium nitrite and heat the mixture.Ammonia gas is given off which turns moist red litmus paper blue.

# data[].attributes.body
Raogenqiang
i. The student wants to filler off the other substances in liquid form from the lead(ii) bromide precipitate.
ii. To remove the impurities on the surface

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The magnesium atom has 2+ electrons , it will lose 2 electrons from magnesium , the sulfur will gain 2 electrons from magnesium .

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（i)The students want to get a pure substance, so they do the filter in order to seperate the residue.
(ii)They want to remove the lead.

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1)Remove the excess substance which can’t dissolve in water
2)Wash off surface impurities

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To obtain pure substance

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To obtain a pure substance of lead (ii) bromide

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A diluted solution of sodium hydroxide is added to the solution and slowly heated. If the root ions are present, they turn into ammonia gas, which turns the wet red litmus paper blue

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ii) to rinse any impurities.

# data[].attributes.body
Han Yining

It is used to remove the residue.
It is to remove the impurities.

# data[].attributes.body
Add a few drops of sodium hydroxide and heat strongly.A pungent gas is released.This gas turns moisten litmus paper into blue

# data[].attributes.body
Add sodium hydroxide it will form a pungent gas and it will turn moist litmus paper into blue

# data[].attributes.body
1. The student need to obtain the precipitate
2. The precipitate needs to get pure substance

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add aqueous solution of NaOH and heat the solution gently a pungent smell is formed

# data[].attributes.body
In order to filter out the excess residue

# data[].attributes.body
Add diluted sodium chloride and heat strongly then a gas come out which turns moist blue litmus paper into red.

# data[].attributes.body
Add a drops of sodium hydroxide and heat strongly.A pungent gas is released.This gas turns moist litmus paper into blue

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(I)0.5mol/dm^3*25.0*10^-3dm^3=0.0125mol
(II)0.0125*24dm^3=0.3dm^3
(III)64
32g/mol

# data[].attributes.body
0.0125

# data[].attributes.body
(I) 0.0125 moles
(II)0.3 dm^3
(III)80     0.00625 g/dm^3

# data[].attributes.body
Add sodium hydroxide solution and heat strongly.A pungent gas is released and it will turns wet red litmus paper into blue.

# data[].attributes.body
Add a few drops of sodium hydroxide. No precipitate forms and ammonia gas is released when heated. When the gas is released place a damp red litmus paper near it and it will turn blue.

# data[].attributes.body
Han Yining

Add a few drops of NaOH and heat strongly. A pungent gas turns moist red litmus paper into blue is formed

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Add sodium hrydroxide and heat. The red litmus paper turn blue

# data[].attributes.body
0.3

# data[].attributes.body
(i)0.0125 moles
(ii)0.3 dm^3
(iii)Mr:64. Conc.=0.8 g/dm^3

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64
32

# data[].attributes.body
0.0125
0.3

# data[].attributes.body
0.0125 mols

# data[].attributes.body
0.0125 mol
0.3 dm3

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i. 2NH4NO3(aq) =4H2O(l)+2NO(g)
ii. When Ammonium nitrate gently heats with sodium hydroxide and aluminium sheets.
iii. the gas which turns red litums paper into blue is given out.

# data[].attributes.body
Han Yining

0.0125
0.3
64, 32

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ii) 0.3 dm^3

# data[].attributes.body
(I)25.0 cm3=0.025dm3
0.025dm3*0.500mol/dm3=0.0125mol
(II)0.0125*24=0.3 dm3

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(b)(i)mole of ammonium nitrite= (25/1000) x 0.5= 0.0125
(ii)  NH4NO2 : N2
1          ;    1
mole of N2 = 0.0125
vol of N2 = 0.0125 x24 = 0.3 dm3

# data[].attributes.body
(I)0.5*0.025=0.0125mol

(II)0.0125*24=0.3dm^3

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iii) relative molecular mass of ammonium nitrate is 64
Concentration of ammonium nitrate is 32 g/dm^3

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Add a few drops of sodium hydroxide into ammonium nitrate , it will no precipitate formed , the ammonia gas will turn moist red litmus paper blue

# data[].attributes.body
(I)2NH4NO3(aq)—————4H2O(l)+2N2O(g)
(II)add aqueous sodium hydroxide to ammonium nitrate solution, warm the mixture with a piece of aluminium foil
Effervescence is observed which turns moist red litmus paper blue

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(a) They have the same 7 number of valence electrons
(b) Their reactivity decreases down the group. They always need to gain one electron to form a bonding with other elements, so when the numbers of electron shells increase they are get harder to gain an electron by intermolecular forces .

# data[].attributes.body
Add a few drops of sodium hydroxide to the aqueous sodium hydroxide and heat strongly,a pungent gas was released which turn moist red litmus paper into blue

# data[].attributes.body
(I)2NH₄NO3(aq)=4H₂O(I)+2NO(g)
(Ii)Chemical Test:The nitrate ion can easily be identified by heating copper turnings along with concentrated sulfuric acid. Effervescence of a brown, pungent gas is observed which turns moist blue litmus paper red.
Results with ammonium nitrate:

# data[].attributes.body
1.0.0125 mol
2.0.3 dm^3
3.Mr=80 0.0125g/dm^3

# data[].attributes.body
weifeng
add Al （s）powder with warm NaOH （aq and heat strongly a pungent gas  which turns moist red litmus paper into blue will be given off

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(II)chemical test:Add aluminum power and sodium hydroxide and heat strongly
Result:A pungent gas which turns moist red litmus paper into blue is released

# data[].attributes.body
They have some valence electrons but different number of shells

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ii) Add aqueous sodium hydroxide followed by aluminium powder. Warm carefully and use damp red litmus paper to test for gas release.

The damp red litmus paper turns blue as pungent alkaline NH3 gas is released.

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weifeng
their valence electrons are all 7

# data[].attributes.body
weifeng
the reactivity decreases down the group
as the size of particles increase the valence electrons shell is away from necleus the attraction of the nucleus decreases

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(a)they all contain seven valence electrons
(b)the reactivity of the halogens decrease down the group as the size of the atoms increases and it is more difficult to gain electrons

# data[].attributes.body
W:silver

X:silver iodide

Y:sodium iodide

Z:sodium chloride

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(I)They have the same valence electrons which are seven.
(II)

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chemical test:Add aluminum power and sodium hydroxide and heat strongly

Result:A pungent gas which turns moist red litmus paper into blue is released

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(a)
W:silver metal
X:silver iodide
Y:sodium iodide
Z:sodium chloride
(b)
2NaI(aq)+Cl2(g)=2Nacl(aq) +I2(s)

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Reactivity decreases down the group. It is because down the group the elements are less readily to lose electrons to form ions due to increase in the size of atomic radius

# data[].attributes.body
W:silver
X:silver iodide
Y:sodium iodide
Z:iodine
(b)2NaI(aq)+Cl2(g)————2NaCl(aq)+I2(aq)

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1.2NH4NO3(aq)=4H2O(l)+2NO2(g)
2.add aqueous sodium hydroxide to ammonium nitrate solution, warm the mixture with a piece of aluminium foil

Effervescence is observed which turns moist red litmus paper blue

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silver
silver iodide
sodium iodide
sodium chloride

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Coke reacts with oxygen to form carbon dioxide as C + O2 — CO2

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decrease down the group