Solving Chemistry Doubts Now :)

[wooowooowoo]

thxxxxxxxxxxx, its correct but if we just draw is thata full mark for the whole question? or do we need to write each Gr atom is bounded by 4 others?

Is there a space given to write the answer? If yes then write it, if not then still write it. No harm

 

[ygyh45]

its just following reactivity series all u need to do is subtract see the drawing

 

[Sajal mehta]

A 5.00 g sample of impure lead(II) nitrate was heated. The volume of oxygen formed was
0.16dm3 measured at r.t.p. The impurities did not decompose.
Calculate the percentage of lead(II) nitrate in the sample.
2Pb(NO3)2 → 2PbO + 4NO2 + O2
Number of moles of O2 formed = .......................................
Number of moles of Pb(NO3)2 in the sample = .......................................
Mass of one mole of Pb(NO3)2 = 331 g
Mass of lead(II) nitrate in the sample = ....................................... g
Percentage of lead(II) nitrate in sample = .....................................
tell me how you got each too please

 

[snoonono]

Is there a space given to write the answer? If yes then write it, if not then still write it. No harm

there r no lines theres just a blank space

 

[ygyh45]

A 5.00 g sample of impure lead(II) nitrate was heated. The volume of oxygen formed was
0.16dm3 measured at r.t.p. The impurities did not decompose.
Calculate the percentage of lead(II) nitrate in the sample.
2Pb(NO3)2 → 2PbO + 4NO2 + O2
Number of moles of O2 formed = .....0.006 moles..................................
Number of moles of Pb(NO3)2 in the sample = .............0.013 moles..........................
Mass of one mole of Pb(NO3)2 = 331 g
Mass of lead(II) nitrate in the sample = ..........4.41............................. g
Percentage of lead(II) nitrate in sample = ..............113 %.......................
tell me how you got each too please

these are my answers check from ms if thy are correct so i can explain otherwise if it ws wrong u have to wait for someone else

 

[edmond]

calcium chloride are soluble or insoluble salt?

 

[ygyh45]

calcium chloride are soluble or insoluble salt?

soluble

 

[Sajal mehta]

to make insoluble salt, all we have to do is react 2 soluble salts??

 

[InternationationalGuy]

(a) Scandium fl uoride is an ionic compound.
(i) The valency of scandium is three. Draw a diagram which shows the formula of the
compound, the charges on the ions and the arrangement of the valency electrons
around the negative ion.
Use x to represent an electron from a scandium atom.
Use o to represent an electron from a fl uorine atom.

The paper is 0620/w_11/62
question 4a

 

[ygyh45]

to make insoluble salt, all we have to do is react 2 soluble salts??

yeah , its the precipitation method or smthing say u want to prepare lead iodide u prepare it using aq.lead nitrate and aq sodium iodide to get lead iodide and sodium nitrate

 

[SB29597]

there r no lines theres just a blank space

4 Ge atoms around 1 Ge [1]
Looks tetrahedral or stated to be
This is what the ms says so you can do either. If it were me I'd draw only if I was sure and also write just in case. Why take a risk?

 

[SB29597]

to make insoluble salt, all we have to do is react 2 soluble salts??

Yes. Precipitation method. Soluble Salt+ Soluble salt = insoluble salt

Oh btw, precipitation means quick/ sudden formation of a precipitate- thats a common question

 

[Maz]

(a) Scandium fl uoride is an ionic compound.
(i) The valency of scandium is three. Draw a diagram which shows the formula of the
compound, the charges on the ions and the arrangement of the valency electrons
around the negative ion.
Use x to represent an electron from a scandium atom.
Use o to represent an electron from a fl uorine atom.

The paper is 0620/w_11/62
question 4a

 

[SB29597]

calcium chloride are soluble or insoluble salt?

soluble. I suggest you go over the carbon cycle

 

[purplerox]

Guys post your doubts- I'll try solving them!!! I WILL BE SO HAPPY TOMORROW!!! (unofficial end of IGCSE's)

soo true...!!
god cant wait for tomorrow..!!

 

[omglaigcse]

HELPHELPHELP.
how do you know a gas is more dense or less dense than air?
what molecular mass are you comparing when you say "air"
is it oxygen or what?

 

[Maz]

HELPHELPHELP.
how do you know a gas is more dense or less dense than air?
what molecular mass are you comparing when you say "air"
is it oxygen or what?

Is this from a past paper? if so, can you give a link.

 

[sammm]

ALL CHLORIDES ARE SOLUBLE EXCEPT SILVER N LEAD CHLORIDE....WELL I GUESS

 

[omglaigcse]

Is this from a past paper? if so, can you give a link.

well i dont know cause im not doing past year papers, im just reading through.
like Carbon dioxide is more dense than air. but what are you comparing to when you say "air"
oxygen and nitrogen is it?

 

[Maz]

well i dont know cause im not doing past year papers, im just reading through.
like Carbon dioxide is more dense than air. but what are you comparing to when you say "air"
oxygen and nitrogen is it?

I think that when we say "air", everything is included . I mean N2, O2, CO2......etc.