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Question-1

Classify the following as pure substances or mixtures separate to pure substances into elements and compounds and divide the mixtures into homogeneous and heterogeneous categories: 
(i) Bronze (ii) Smoke (iii) Pencil lead (iv) Antenna rod

Solution:
(i) Bronze = a mixture of Cu & Sn - Homogenous mixture.
(ii) Dust = a mixture of carbon particle and air - Heterogenous mixture.
(iii) Pencil lead = Pure element - Graphite.
(iv) Antenna rod = Aluminium.

Question-2

Calculate number of moles for the following ?  
(i) 360 gms of H2O (ii) 5.6 gms of Nitrogen (iii) 4 gms of NaOH
.

Solution:
(i) No. of moles of H2O = = = 20;

(ii) Number of moles of N2 = = 0.2;
(iii) Number of moles of NaOH = = 0.1.

Question-3

Calculate the number of moles of H2SO4 present in 50 ml of 0.2m H2SO4.

Solution:
0.2m means it contains 0.2 moles per litre.

1000 ml contains 0.2 moles at H2SO4

50 ml contains = x 50 = = 10 ×10-2  =  0.01 moles.

Question-4

What is molarity of a solution contain 5.84 gms of NaCl in 200 ml of solution?

Solution:
Number of moles of NaCl = = = 0.1

                         Molarity =

Volume of solution in litre = = 0.2

Molarity of the solution = = = 0.5m.

Question-5

What is weight of NaOH present in 250 cc of a 2M solution?

Solution:
2M of NaOH solution means it contains 2 moles of NaOH per litre

                             1000ml = 2 moles of NaOH

Number of moles of NaOH present in 250cc =  =  0.5

                              Mole = ; wt   = mole x m.wt

Weight of NaOH present in 250 ml of solution = 0.5 x 40 = 20 gm.

                                         / Through Formula /

Weight of substance in 1 lit solution               = Molarity x m.wt

Weight of NaOH present in 1 lit solution         = 2 x 40 gms

Weight of NaOH present in 250cc solution =  = 20 gms.

Question-6

In a reaction vessel 0.980 gm of H2SO4 is required to be added for completing the reaction. How many millilitre of 0.05 M H2SO4 solution should be added for this requirement?

Solution:
0.05 M H2SO4 means 0.05 moles of H2SO4 pressure in 1000 ml;

1 litre of 0.05 m H2SO4 contains = molarity x m.wt = 0.05 x 98 = 5 x 10-2 x98 = 4.9 gms of H2SO4

1 ml contains =            = 4.9 x10-3 gms of H2SO4
4.9 x of gms of H2SO4      = 1 ml of solution

0.980 gms of H2SO4             = = = 2 x 102 = 200 ml.

Through formula :

Wt. of H2SO4 present in 1 lt    = Molarity x m.wt

Wt.of H2SO4 present in 1 lt of 0.05M = 0.05 x 98 gm = 98 x 5 x 10-2 gms = 4.9 gms.

4.9 gms is present in 1000 ml

Hence, 0.980 gms is present in
                                             =
                                             = 200 ml.

Question-7

How much AgCl will be formed by adding 200ml of 5M HCl to the solution containing 1.7 gms of Ag No3?

Solution:
 

AgNO3 + HCl AgCl + HNO3

200 ml of 5M HCl contains 1.7g of AgNO3

1000 ml of 1M HCl will contain = 1.7g

Hence 1M solution of HCl contains 1.7 g of AgNO3.

Question-8

Calculate the weight of HCl in 10 ml of con. HCl of density 1.2 gm L-1 container 35% HCl by weight. What is the molarity of the solution?

Solution:
35% HCl means 35 gm of HCl are present in 100 gms of HCl solution.

Volume of 100 gms of given HCl solution = =  = 83.3 ml

83.3 ml of con. HCl contains 35 gms of HCl

10 ml of con. HCl contains = = 4.20 gms of HCl.

Molarity of the solution = (in litre)
                                 =
                                 = = 1.15 M.

Question-9

The molarity of con. HCl is 1.15M; what volume of con. HCl is required to make 1.00 of 0.1M HCl.

Solution:
Known Unknown

V1 M1 = V2 M2

1000 ml x 0.1M = V2 x 1.15M

V2 = ml = = = 86.9 ml.

Question-10

Aluminium and Sulphuric acid react according to the reaction :

If 0.5 mol Al are added to H2SO4 solution containing 0.2 mole H2SO4 , how many moles of H2 are produced.

Solution:
As per equation, 2 moles Al reacts with 3 moles of H2SO4 to produce 3 mole of H2.

0.5 ml Al reacts with 3 mole of H2SO4 moles of H2.

0.5 ml of Al reacts with 0.2 mole of H2SO4 = mole of H2
                                                                     = moles of H2
                                                                     = = 0.4 moles of H2.





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