Chemistry 9701 Multiple choice questions

[Anam Ayesha Khan]

Two reactions and their enthalpy changes are shown.
2C(s) + 2H2(g) → C2H4(g) ∆Ho = +52.2 kJ mol–1
C2H2(g) + H2(g) → C2H4(g) ∆Ho = –175.8 kJ mol–1
These data can be used to calculate the enthalpy change for the reaction shown.
2C(s) + H2(g) → C2H2(g) ∆Ho= X
What is the value of X?
A –228.0 kJ mol–1
B –123.6 kJ mol–1
C +123.6 kJ mol–1
D +228.0 kJ mol–1

I need the full method please...(THE ANSWER IS D)

 

[Anam Ayesha Khan]

In which species is there a lone pair of electrons?
A. CH3
B. CH3+
C. CH3–
D. CH4

I need explanation for this please..(THE ANSWER IS C)

 

[Anam Ayesha Khan]

The reaction of bromine with warm NaOH(aq) produces products with the same oxidation numbers, in the same ratios, as the reaction of chlorine with hot NaOH(aq).In one reaction between bromine and warm NaOH(aq), 30.2 g of a product containing sodium,
bromine and oxygen is produced.
Which mass of NaOH has reacted?
A. 8.00 g
B. 10.2 g
C. 20.3 g
D. 48.0 g

I need full method and explanation on how to solve this please..(THE ANSWER IS D)

 

[Anam Ayesha Khan]

The reaction between sulfur dioxide and oxygen is reversible.
2SO2(g) + O2(g) 2SO3(g) Kc = 280 mol–1 dm3 at 1000K
In an equilibrium mixture at 1000K the sulfur trioxide concentration is 6.00mol dm–3.
The sulfur dioxide concentration is twice the oxygen concentration.
What is the sulfur dioxide concentration?
A 0.175 mol dm–3
B 0.254 mol dm–3
C 0.318 mol dm–3
D 0.636 mol dm–3

I need the explanation and full method please..(THE ANSWER IS D)

 

[Anam Ayesha Khan]

Four elements, W, X, Y and Z, have electronic configurations as shown.
W X Y Z
2,4 2,6 2,8,2 2,8,8,1
Which formulae represent compounds that have boiling points below room temperature?
1 WX2
2 YX
3 Z2X

I need explanation for this please.. ( It says option 1 is the answer)

 

[vedette]

In which species is there a lone pair of electrons?
A. CH3
B. CH3+
C. CH3–
D. CH4

I need explanation for this please..(THE ANSWER IS C)

i got an explanation for this one.you know carbon has four electrons available for pairing right? so it pairs 3 of its electrons with 1 electron each from the 3 hydrogens to form three pairs.so it will have one unpaired electron.the negative symbol shows us that it has gained one electron.that one electron gained plus the original single unpaired electron form one lone pair

 

[Anam Ayesha Khan]

i got an explanation for this one.you know carbon has four electrons available for pairing right? so it pairs 3 of its electrons with 1 electron each from the 3 hydrogens to form three pairs.so it will have one unpaired electron.the negative symbol shows us that it has gained one electron.that one electron gained plus the original single unpaired electron form one lone pair

thanks

 

[Anam Ayesha Khan]

i got an explanation for this one.you know carbon has four electrons available for pairing right? so it pairs 3 of its electrons with 1 electron each from the 3 hydrogens to form three pairs.so it will have one unpaired electron.the negative symbol shows us that it has gained one electron.that one electron gained plus the original single unpaired electron form one lone pair

if you could answer my other questions,it would be good..thanks

 

[Anam Ayesha Khan]

An excess of chlorine was bubbled into 100 cm3 of hot 6.0 mol dm–3 sodium hydroxide.
How many moles of sodium chloride would be produced in the reaction?
A 0.3
B 0.5
C 0.6
D 1.2

I need the working and explanation for this please.(the answer is B)

 

[Anam Ayesha Khan]

A small quantity of hot, concentrated sulfuric acid is added separately to solid samples of potassium halides, KX.
Which potassium halides react and produce a mixture of products that include a halogen, X2?
1 potassium iodide
2 potassium bromide
3 potassium chloride

(the answer is saying 1 and 2 are correct). I need explanation for this please

 

[vedette]

thanks

u r welcome

 

[vedette]

if you could answer my other questions,it would be good..thanks

ok i'll try

 

[Leonide]

Could you please help me out with this question 😐 ?

X, Y and Z are all gases that behave ideally and react according to the equation shown. X(g) + 2Y(g) → 2Z(g) When 3.0 mol of X and 3.0 mol of Y are placed inside a container with a volume of 1.0 dm3, they react to form the maximum amount of Z. The final temperature of the reaction vessel is 120 °C. What is the final pressure inside the reaction vessel?
The answer is 1.47 * 10^7 Pa

 

[vedette]

Two reactions and their enthalpy changes are shown.
2C(s) + 2H2(g) → C2H4(g) ∆Ho = +52.2 kJ mol–1
C2H2(g) + H2(g) → C2H4(g) ∆Ho = –175.8 kJ mol–1
These data can be used to calculate the enthalpy change for the reaction shown.
2C(s) + H2(g) → C2H2(g) ∆Ho= X
What is the value of X?
A –228.0 kJ mol–1
B –123.6 kJ mol–1
C +123.6 kJ mol–1
D +228.0 kJ mol–1

I need the full method please...(THE ANSWER IS D)

i think u construct a multi step reaction circle(born haber cycle) since C + H2 → C2H4 and C2H2 +H2 → C2H4
so i guess at the end of the day u subtract -175.8 fom 52.2 to give you 228
sorry not to sure how to explain it futher

 

[vedette]

The reaction of bromine with warm NaOH(aq) produces products with the same oxidation numbers, in the same ratios, as the reaction of chlorine with hot NaOH(aq).In one reaction between bromine and warm NaOH(aq), 30.2 g of a product containing sodium,
bromine and oxygen is produced.
Which mass of NaOH has reacted?
A. 8.00 g
B. 10.2 g
C. 20.3 g
D. 48.0 g

I need full method and explanation on how to solve this please..(THE ANSWER IS D)

sorry i don't know

 

[vedette]

The reaction between sulfur dioxide and oxygen is reversible.
2SO2(g) + O2(g) 2SO3(g) Kc = 280 mol–1 dm3 at 1000K
In an equilibrium mixture at 1000K the sulfur trioxide concentration is 6.00mol dm–3.
The sulfur dioxide concentration is twice the oxygen concentration.
What is the sulfur dioxide concentration?
A 0.175 mol dm–3
B 0.254 mol dm–3
C 0.318 mol dm–3
D 0.636 mol dm–3

I need the explanation and full method please..(THE ANSWER IS D)

i think well you say the o2 conc is x and the so2 conc is 2x so i guess you substitute as follows and get your answer
kc= [s03]/[02]x[s02]^2

 

[vedette]

Four elements, W, X, Y and Z, have electronic configurations as shown.
W X Y Z
2,4 2,6 2,8,2 2,8,8,1
Which formulae represent compounds that have boiling points below room temperature?
1 WX2
2 YX
3 Z2X

I need explanation for this please.. ( It says option 1 is the answer)

ok first of all let's identify all the elements
W-2+4 → 6 → carbon
X-2+6 → 8 → oxygen
Y-2+8+2 → 12 → magnesium
Z-2+8+8+1 → 19 → potassium
so they asked us which compound would have boiling points lower than room temp(25 oc).so basically the compound is supposed to be a convelently bounded compound.and from what we deduced WX2 would be CO2,YX would be MgO and Z2x would be K2O. so that means our answer is wx2 because it represents CO2 which is a covelently bounded compound and most covelent compounds normally have low boiling points

 

[vedette]

An excess of chlorine was bubbled into 100 cm3 of hot 6.0 mol dm–3 sodium hydroxide.
How many moles of sodium chloride would be produced in the reaction?
A 0.3
B 0.5
C 0.6
D 1.2

I need the working and explanation for this please.(the answer is B)

are you sure the answer is b?

 

[vedette]

A small quantity of hot, concentrated sulfuric acid is added separately to solid samples of potassium halides, KX.
Which potassium halides react and produce a mixture of products that include a halogen, X2?
1 potassium iodide
2 potassium bromide
3 potassium chloride

(the answer is saying 1 and 2 are correct). I need explanation for this please

honestly IDK

 

[Anam Ayesha Khan]

ok first of all let's identify all the elements
W-2+4 → 6 → carbon
X-2+6 → 8 → oxygen
Y-2+8+2 → 12 → magnesium
Z-2+8+8+1 → 19 → potassium
so they asked us which compound would have boiling points lower than room temp(25 oc).so basically the compound is supposed to be a convelently bounded compound.and from what we deduced WX2 would be CO2,YX would be MgO and Z2x would be K2O. so that means our answer is wx2 because it represents CO2 which is a covelently bounded compound and most covelent compounds normally have low boiling points

Thank you...