" /> -->

#### internal

11th Standard

Reg.No. :
•
•
•
•
•
•

Chemistry

Time : 01:00:00 Hrs
Total Marks : 50
parti
3 x 1 = 3
1. Assertion: Fluorine has an oxidation state of - 1in all its compounds.
Reason: Fluorine is the most electronegative element of the periodic table.

(a)

Both assertion and reason are correct and the reason is the correct explanation for the assertion.

(b)

Both assertion and reason are correct but reason is not the correct explanation for the assertion

(c)

Assertion is true but reason are false.

(d)

Both assertion and reason are false.

2. The oxidation number of oxygen in O2 is _______________

(a)

0

(b)

+1

(c)

+2

(d)

-2

3. Rusting of iron articles is an example of ___________ reaction

(a)

Combustion

(b)

decomposition

(c)

redox

(d)

hydrolysis

4. part 2
6 x 2 = 12
5. Distinguish between oxidation and reduction.

6. The density of carbon dioxide is equal to 1.965 kgm-3 at 273 K and 1 atm pressure. calculate the molar mass of CO2

7. Calculate the average atomic mass of naturally occurring magnesium using the following data

Isotope Istopic atomic mass Abundance(%)
Mg24 23.99 78.99
Mg26 24.99 10.00
Mg25 25.98 11.01
8. Give a brief account of classification of matter.

9. Distinguish between a homogeneous and heterogeneous mixture.

10. Mention the characteristics of a compound.

11. part 3
6 x 3 = 18
12. Mass of one atom of an element is 6.645 x 10-23g. How many moles of element are there in 0.320 kg.

13. What is the empirical formula of the following?
i) Fructose (C6 H12O6) Found in honey
ii) Caffeine  (C8H10N4 O2) a substance found in tea and Coffee

14. How would you know whether a redox reaction is taking place in an acidic, alkaline or neutral medium?

15. What is the most essential conditions that must be satisfied in a redox reaction?

16. How many moles of ethane is required to produce 44 g of CO2(g) after combustion

17. Consider the reactions,
(i) H3PO2(aq) + 4AgNO3(aq)+ 2H2O(l) $\longrightarrow$ H3PO4(aq)+ 4Ag(s)+ 4HNO3(aq)
(ii) H3PO2(aq) + 2CuSO4(aq) + 2H2O(l) $\longrightarrow$ H3PO4(aq)+ 2Cu(s) + H2SO4(aq)
(iii) C6H5CHO(l) + 2[Ag(NH3)2]+(aq) + 3OH-(aq)  $\longrightarrow$ C6H5COO-(aq) + 2Ag(s)+ 4NH3(aq) + 2H2O(l)
(iv) C6H5CHO(l) + 2Cu2+(aq) + 5OH-(aq) $\longrightarrow$ No change observed.
What interference do you draw about the behavior of Ag+ and Cu2+ from these reactions?

18. part4
4 x 5 = 20
19. The reaction between aluminum and ferric oxide can generate temperatures up to 3273 K and is used in welding metals. (Atomic mass of AC = 27 u atomic mass of O = 16 u )
2Al + Fe2O3 $\longrightarrow$ Al2O3 + 2Fe;  If in this process, 324 g of aluminum is allowed to react with 1.12 kg of ferric oxide
i) Calculate the mass of Al2O3 formed
ii) How much of the excess reagent is left at the end of the reaction?

20. A Compound on analysis gave Na = 14.31% S = 9.97% H= 6.22% and 0= 69.5% calculate the molecular formula of the compound if all the hydrogen in the compound is present in combination with oxygen as a water of crystallization. (molecular mass of the compound is 322).

1. Balance the following equations by ion electron method -
i) ${ KMn }O_{ 4 }+{ SnCl }_{ 2 }+HCI\longrightarrow MnCI_{ 2 }+{ SnCI }_{ 4 }+{ H }_{ 2 }O+KCI$
ii) ${ C }_{ 2 }{ O }_{ 4 }^{ 2- }+{ Cr }_{ 2 }{ O }_{ 7 }^{ 2- }\longrightarrow { Cr }^{ 3+ }+{ CO }_{ 2 }$ (in acid medium)
iii) ${ Na }_{ 2 }{ S }_{ 2 }{ O }_{ 3 }+{ I }_{ 2 }\longrightarrow { Na }_{ 2 }{ S }_{ 4 }{ O }_{ 6 }+NaI$
iv) $Zn+{ NO }_{ 3 }^{ - }\longrightarrow { Zn }^{ 2+ }+No$

2. Balance the following equations by oxidation number method.
Ag + HNO3 ⟶ AgNO3 + H2O + NO