TYS 'O' LVL chem questions

eagle SG

d) calcium carbonate is insoluble in water.name two sustance that, when mixed in solution will form a precipitate of calcium carbonate?

I not very sure. Forgot a lot of chem

I guess his answer of calcium chloride and sodium carbonate should be correct

you have to take 2 salts that are soluble in water to mix together

gunner77 SG

oops not this question

i mean the relative molecular mass question. sorry.

eagle SG

His answer

3a) relative molecular mass of a compound is the average mass of one molecule of the substance compared to 1/12 the mass of carbon-12 atom

This is because Carbon-12 atom has it's molecular mass at 12. It is sort of used as the standard measurement.

1/12 of the molecular mass of the carbon-12 atom means molecular mass of 1.

Relative molecular mass, the key word is in the 'relative'. So saying that it is relative to 1/12 of carbon atom; carbon-12 atom is the reference mass.

gunner77 SG

ok i tink i roughly get it. thanks alot guys !

eagle SG

gd luck

dun waste my effort of doing undelete in my brain for some chemistry knowledge

gunner77 SG

just hope tat watever the TYS has

will come out

*basic oxide and amptheoric oxide react with acid to form salt and water

* only amptheoric oxide react with alkaline to form salt and water

ok i must rmb this two points.

maurizio13 SG

230pm

im scared

fasterly go middle road guan yin temple pray.

UltimaOnline SG

LAST MINUTE 'O' LEVEL QN!!!

In one molecule of ammonia, how many electrons involved in bonding, how many electrons not involved in bonding?

Ans : (I'll reveal later if no one can get it right... but simple qn lah, u BETTER get it right)

Ah sian SG

nh3 = 4 atom

nitrogen = 2.8.4

h3 = 3 molecue

3 reacting 1 not reacting isit

wishboy SG

LAST MINUTE 'O' LEVEL QN!!!

In one molecule of ammonia, how many electrons involved in bonding, how many electrons not involved in bonding?

Ans : (I'll reveal later if no one can get it right... but simple qn lah, u BETTER get it right)

6 electrons involved, 2 not involved.

Ah sian SG

how u get

wishboy SG

Ah sian SG

shit i thought electron is nucleon

die liao

davidche SG

LAST MINUTE 'O' LEVEL QN!!!

In one molecule of ammonia, how many electrons involved in bonding, how many electrons not involved in bonding?

Ans : (I'll reveal later if no one can get it right... but simple qn lah, u BETTER get it right)

how many valence electrons you mean?

davidche SG

shit i thought electron is nucleon

die liao

I can spot another mistake. And you tot nucleon is neutron?

gunner77 SG

5 years of secondary education

it just boils down to the 1h15min

Ah sian SG

I can spot another mistake. And you tot nucleon is neutron?

what u mean nucleon is neutron

where u spot from my post

i thought nucleon is aka mass

neutron is nucleon - proton

Ah sian SG

i very scare leh

Ah sian SG

i really very scare leh

gunner77 SG

relax relax.

just do ur paper, mind ur own business.

don look left right centre, just focus.

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