chem MCQ plz help

[robinho10]

Q1.which species does not have four or more atoms in the same plane?
A. ALF^-3
B.BF3
C.SF6
D.SiF4

answer is D why is it ?

Q2.the reaction of chlorine with ot conc. aqeous sodium hydroxide produces oxoanion as one of the product. this oxoanion is used as a weed killer , which statement is corret
A. it contains chlorine in the +1 oxidation state
B.it contains chlorine in the +5 oxidation state
C. it is planar in shape
D. it is tetrahedral in shape

answer is B why is it and wat r oxoanions?
Q3.acid rain formed from SO2 contain 2 sulphur oxoanions after a while , what r the oxidation states of sulphur in these oxoaniions?
A. 0 and 2
B. 2 and 4
C. 4 and 5
D. 4 and 6

answer is D why is it and wat r oxoanions again?

Q4. AS a simplification an adult human can be considered to have a daily diet of 1.80kg of carbohydrate(empirical formula CH2O) , which mass of the carbon dioxide does a person produce each day if alll the carbohydrates eaten is digested and oxidised?
A.0,267
B.0.800
C.1.32
D.2.64

answer is D plz explain and working

Q5. flask X contain 1dm3 of helium at 2KPA pressure and flask Y contains 2dm3 of neon at 1kPA pressure , if the flask are connected at constant temp. what is the final pressure?
A.1 1/3
B. 1.5
C.1 2/3
D.2

answer is A plz explain and working

Q6.use data booklet for this question ,

what is enthaply change of atomisation of 1mol of gaseous hydrazine?
A.550KJ
B.1720KJ
C.1970KJ
D.2554KJ

answer is B plz explain n working

Q7. what is the total number of diffferent chloroethanes(formula C2H6-nCln) where n can be integer from 1 to 6 ?
A.6
B.8
C.9
D.10

answer is D plz explain

Q8.a mixture of 10cm3 of methane and 10cm3 of ethene was sparked with an excess of oxygen after cooling at room temp. the residual gag was passed through aqeous potassium hydroxide , what vollume of gas was absorbed by the alkali ?
A.15cm3
B.20cm3
C.30cm3
D,40cm3

answer is C plz working

 

[workinghard]

1 tetrahydral arrangement one F is behind da plane n one in front of it
2 NaClO3 is produced n oxidation state is +5 mayb anion contain oxygen atoms ..not sure botu this
3 in So2 +4 since 2 oxygen atoms each wid -2 n in SO3 +6 as 3 O atoms
i ll attach da working of others soon... it ll b easier

 

[CommonSense]

because the shape of D is tetrahedral. You gotta imagine the 3D shape and that u removed some atoms to mke it a 2D shape. Count the number of atoms in the flat shape u get. With D it is Si and 2 flourines

because chlorine reacts with hot concentrated NaOH to give the chlorate(v) ion ie ClO3- which is used as a weed killer, the oxidation of chlorine in this anion is +5 and oxoanion is just a fancy name for an anion with an oxygen !

the oxoanions are the SO42- AND SO32- (bec we get both sulphuric and sulfurous acids) the oxidation state of sulfur in the first one is +6 and in the second one +4

Find the Mr of the empirical formula ie 30
Divide the number of kg of the carbohydrate by the Mr to get the number of moles of the carbohydrate
As the mole ratio of the carbohydrate to carbon dioxide is 1 : 1, multiply the number of moles by the Mr of CO2 to get the mass in kg
1.8/30 = 0.06
0.06 * 44 = 2.64 kg

I was stuck at this question too but here is what i came up with:
The sum of the volumes is 3dm3
The total pressure will be greater than 1 but less than 2
So like the formula of the mass spectrometer do this: {(vol1*pressure1) + (vol2*pressure2)}/ sum of volumes[(1*2)+(2*1)]/3 = 4/3

You have 1 N-N bond and 4 N-H bond to be broken (endothermic)
{160+(4*390)}

on a sheet of paper draw the dispalyed structural formulae for the six formulas.
For each compound draw all the structural isomers and u will get 9 different compounds. they are
CH3CH2Cl
CH2ClCH2Cl
CHCl2CH3
CCl3CH3
CHCl2CH2Cl
CHCl2CHCl2
CCl3CH2Cl
CHCl2CCl3
CCl3CCl3

30 dm3 of carbondioxide will be produced (10 from methane and 20 from ethane) and as it is acidic it will be absorbed by the alkali

 

[workinghard]

well i wx gonna rply now but common sense xplnd it all so salute to commonsense

 

[sweetiepie]

thanks...