#### Basic Concepts of Chemistry and Chemical Calculations Important Question Paper

11th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 50
5 x 1 = 5
1. 40 ml of methane is completely burnt using 80 ml of oxygen at room temperature The volume of gas left. after cooling to room temperature is

(a)

40 ml CO2 gas

(b)

40 ml CO2 gas and 80 ml H2O gas

(c)

60 ml CO2 gas and 60 ml H2O gas

(d)

120 ml CO2 gas

2. An element X has the following isotopic Composition 200X = 90%, 199X = 8% and 202X = 2% The Weighted average atomic mass of the element X is closet to

(a)

201 u

(b)

202 u

(c)

199 u

(d)

200 u

3. Assertion: Two mole of glucose contains 12.044 x 1023 molecules of glucose
Reason: Total number of entities present in one mole of any substance is equal to 6.02 x 1022

(a)

both assertion and reason are true and the reason is the correct explanation of assertion

(b)

both assertion and reason are true but the reason is not the correct explanation of assertion

(c)

an assertion is true but reason is false

(d)

both assertion and reason are false

4. The oxidation number of hydrogen in LiH is _____________

(a)

+1

(b)

-1

(c)

+2

(d)

-2

5. The oxidation number of Cr in Cr2O72- __________ is

(a)

+6

(b)

-6

(c)

+7

(d)

-7

6. 6 x 2 = 12
7. Distinguish between oxidation and reduction.

8. 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

9. Which contains the greatest number of moles of oxygen atoms
i) 1 mol of ethanol
ii) 1 mol of formic acid
iii) 1 mol of H2O

10. Give examples for the following redox reaction "Combination".

11. Give examples for the following redox reaction "Decomposition".

12. Give examples for the following redox reaction "Metal displacement reaction".

13. 6 x 3 = 18
14. Mass of one atom of an element is 6.645 x 10-23g. How many moles of element are there in 0.320 kg.

15. What is the difference between molecular mass and molar mass? Calculate the molecular mass and molar mass for carbon monoxide.

16. 2Cu2S + 3O2 $\longrightarrow$ 2Cu2O + 2SO2
(i) In this reaction which substance is getting oxidised and which substance is getting reduced?
(ii) Name the oxidising and reducing agents.

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

18. Why is anode called oxidation electrode, whereas the cathode is called reduction electrode?

19. Calculate the amount of water produced by the combustion of 32 g of methane.

20. 3 x 5 = 15
21. 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?

22. Balance the following equations by oxidation number method.
P + HNO3 ⟶ HPO3 + NO + H2O

23. Balance the following equations by oxidation number method.
KIO3 + SO2 + H2O ⟶ KHSO4 + H2SO4 + I2