Monday, 2 March 2020

PLUS ONE CHEMISTRY QUESTIONS AND ANSWERS

Chapter 7
         EQUILIBRIUM

1.  The acid  that results when a base accepts proton is called

Ans:- conjugate acid of the base

2. Which one of the following has pH value of 10.5?

a. Lime water
b. Soft drink
c. Blood
d. Milk

Ans:- lime water

3. According to Lewis concept an acid is an  electron pair donor.  State whether this statement true or False

Ans:- False,  according to Lewis concept an acid is an electron pair acceptor

4. Which of the following will favor the reverse reaction in a chemical equilibrium
a. Increas in the concentration of  one or more of the product
b.  increase in presser
c.  Decreas in the pressure

Ans:- a

5. 1 l of water, 10^ -3 mol of Hcl is added  The pH of the solution is

Ans:- 7

6. Observe the  relationship between the first two terms and filling the blanks

CH3COONa: alkaline ,pH >7
NaNO3: ...............

Ans:- neutral pH = 7

7. Choose the correct pair
Liquid vapour : melting
Solid liquid : boiling point
Solid vapours: sublimation point

Ans:- solid vapours : sublimation point

8.  Which of the following statement  regarding a catalyst  in a equilibrium presses is currect ?

a. Increase the forword reaction
b. Increase the backward reaction
c. It hastens the easy attainment of equilibrium

Ans:- c

9. The ph of neutral water is 6.5. Then temperature of the water is

Ans:- more than 25°c

10. The aqueous solution of HCOONa,C6H5NH3Cl and kCN are respectively

Ans:- basic, acids,basic

11.The blue litmus paper dipped into a aqueous solution of NH4NO3 . Is there any colour change .substantiate your answer

Ans:- yes blue litmus paper changes to red
NH4NO3 is a salt formed from a weak base and a strong  acid  so on hydrolysis gives an acidic solution

12. To a basic buffer solution 3 drops of  0.1 M Hcl solution is added .still its pH  remain
Same for the observation

Ans:- Buffer is a solution which resists change in pH by the addition of  small amount of  acid or base .Here the H+ ion from the acid will be neutralised by the buffer

13. When some sodium acetate is added to a solution of acetic acid .the  concentration of unionised  acetic acid increases .what is the phenomenon involved have ? substantiate

Ans:- common ion effect. The dessosiation of acetic acid is suppressed by the common ion CH3COO which compines with H to form acetic acid

14. Select the sutable reagent . Prepare the basic buffer and an acidic buffer

NH4Cl,NH4OH,NaOH, NaCl, CH3COOH,CH3COONa

Ans:- Acidic buffer:- CH4COOH+CH3COONa
          Basic buffer:- NH4Cl,NH4OH

15. During a class room discussion one your friends argues that ionic product of water is not altered with the change in temperature
What is your view towards this argument .justify

Ans:- The argument is wrong .ionic product of water kw increases with increases in temperature since the dissociation  of water is an endothermic process



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