Chemistry: Post your doubts here!

[ShahdNaasan]

I had the same problem in this question when I solved this paper but now after repeated tries I was able to solve it correctly Alhamdulillah.
First find the value of the constant K as the angle of deflection is directly proportional to the charge mass ratio
PROTON:
Angle=+15 Charge= + mass= 1
15= k(+/1) thus K=+15

Option 1 :
Charge= +1-2= -1
mass= (atomic mass) 1+2=3
k=+15
Angle= (+15)*(-1/3)= -5..............option 1 correct

Option 2 :
Charge = +3-5 = -2
mass=3+3 =6
K=+15
Angle = (+15)*(-2/6) = -5..................option 2 is also correct

Option 3 :
Charge :4-1 = +3
mass=4+5 =9
K=+15
Angle = (+15)*(+3/9) = +5.......................Option 3 is incorrect.

Ans: B

Thank you so much.
Really appreciated.

 

[Aishayasin]

A large excess of marble chips was reacted with 25 cm3 of 1.0 mol dm–3 hydrochloric acid at 40 °C. How will the result be different when the reaction is repeated with 60 cm3 of 0.5 mol dm–3 hydrochloric acid at 40°C?
A The reaction is faster and less of the products are made.
B The reaction is faster and more of the products are made.
C The reaction is slower and less of the products are made.
D The reaction is slower and more of the products are made.

Answer is D plz help I dont understand the part more product

 

[Aishayasin]

QUESTION 35 ANWER IS OPTION D THAT IS 1

 

[A*****]

A large excess of marble chips was reacted with 25 cm3 of 1.0 mol dm–3 hydrochloric acid at 40 °C. How will the result be different when the reaction is repeated with 60 cm3 of 0.5 mol dm–3 hydrochloric acid at 40°C?
A The reaction is faster and less of the products are made.
B The reaction is faster and more of the products are made.
C The reaction is slower and less of the products are made.
D The reaction is slower and more of the products are made.

Answer is D plz help I dont understand the part more product

The temperature is the same so it does not affect
In the 2nd reaction, the concen. is lower so the reaction will be slower
The number of moles in 2 is greater so more product os formed

 

[A*****]

View attachment 63707
QUESTION 35 ANWER IS OPTION D THAT IS 1

35 or 39?

 

[saitama]

can anyone predict solids and solutions for 34

 

[blymphocytes]

Guidance on how to solve these question.
17. 71.0 g of chlorine, Cl 2, react with an excess of sodium hydroxide solution at a particular temperature. The reaction produces exactly 35.5 g of product X.
What is product X?
A H 2O B NaCl C NaCl O D NaCl O3

8. Sulfur can be oxidised in two ways.
S(s) + O2(g) → SO2(g) ∆H o = –296.5 kJ mol–1 2S(s) + 3O2(g) → 2SO3(g) ∆H o = –791.4 kJ mol–1

Sulfur trioxide can be made from sulfur dioxide and oxygen.

2SO2(g) + O2(g) → 2SO3(g)

What is the standard enthalpy change for this reaction?
A –1384.4 kJ mol–1 B –989.8 kJ mol–1 C –494.9 kJ mol–1 D –198.4 kJ mol–1

 

[Hamnah Zahoor]

17. 71.0 g of chlorine, Cl 2, react with an excess of sodium hydroxide solution at a particular temperature. The reaction produces exactly 35.5 g of product X.
What is product X?
A H 2O B NaCl C NaCl O D NaCl O3

When ever chlorine gas is involved Ar of Chlorine 71.0 is to be used
Make up equations for both
3Cl2 + 6NaOH----------> NaClO3 + 5NaCl + 3H2O
Moles of chlorine 71/71= 1 mole
Moles of chlorine ratio NaClO3
Cl2: NaClO3
3 : 1
(1/3)*(106.5) = 35.5 g
Thus D is the correct option.

 

[blymphocytes]

T

When ever chlorine gas is involved Ar of Chlorine 71.0 is to be used
Make up equations for both
3Cl2 + 6NaOH----------> NaClO3 + 5NaCl + 3H2O
Moles of chlorine 71/71= 1 mole
Moles of chlorine ratio NaClO3
Cl2: NaClO3
3 : 1
(1/3)*(106.5) = 35.5 g
Thus D is the correct option.

Thanks Hamnah .......could you please explain the next one as well?

 

[Hamnah Zahoor]

T

Thanks Hamnah .......could you please explain the next one as well?

 

[blymphocytes]

View attachment 63709

Thank you so much!! <3
You're amazingg xoxo

 

[Hamnah Zahoor]

Thank you so much!! <3
You're amazingg xoxo

I am glad it helped you.

 

[Hamnah Zahoor]

View attachment 63707
QUESTION 35 ANWER IS OPTION D THAT IS 1

For statement 1 The following website will help you understand it in a more better way
https://www.chemguide.co.uk/mechanisms/nucadd/hcn.html


Thus, Statement 1 correct.

For statement 2 :
The initiating step is the nucleophile CN- attacking the partial positive carbon NOT the proton (H+) being transferred to oxygen.
For statement 3 :
Only aldehydes or ketone react with the Cyanide ion not esters. ( thus only one group reacts)

 

[innovative_1]

Can someone plsss tell how to balance this equation by oxidation number?

 

[A*****]

Can someone plsss tell how to balance this equation by oxidation number?

It is easier to do it by balancing electrons

 

[innovative_1]

It is easier to do it by balancing electrons

Yeah i totally agree with u i can even easily solve A2 electrochemistry lol but this one i just can't able to form half equations plss can u just show it's working i would get it

 

[A*****]

Yeah i totally agree with u i can even easily solve A2 electrochemistry lol but this one i just can't able to form half equations plss can u just show it's working i would get it

Such equations are very odd...I think we have to do them by hit and trial method

 

[innovative_1]

Such equations are very odd...I think we have to do them by hit and trial method

I never heard abt this method before

 

[dumbledore.]

6 A substance commonly found in the house or garden has the following properties.
• It is combustible.
• It is an electrical insulator.
• It melts over a range of temperature.
What could the substance be?
A brass
B paper
C poly(ethene)
D silicon(IV) oxide
Ans is C

 

[A*****]

I never heard abt this method before

That is simple guessing...putting the values given in the options one by one and seeing if the equation balances
https://chemtutorial.wordpress.com/tag/hit-and-trial-method/