81.  For a reaction , the amount of C formed by starting the reaction with 5 moles of A and 8 moles of B is

A. 5 moles

B. 8 moles

C. 16 moles

D. 4 moles

Answer : Option D

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82.  100 mL of on heating forms P and . The volume change in the reaction is

A. an increase of 50 mL

B. an increase of 100 mL

C. an increase of 150 mL

D. a decrease of 50 mL

Answer : Option A

Explanation :

2 mL                               3mL

100 mL                        (?)

                                     

Increase = 50 mL

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83.  An organic compound made of C, H, and N contains 20% nitrogen. Its molecular weight is (WB JEE 2009)

A. 70

B. 140

C. 100

D. 65

Answer : Option A

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84.  Volume occupied by one molecule of water is

A.

B.

C.

D.

Answer : Option C

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85.  Calculate the number of moles in gas at STP.

A. 4.46

B. 44.6

C. 446

D. 4460

Answer : Option B

Explanation :

= 1000L

At STP, 22.4 L = 1 mol

 1000 L = = 44.6

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86.  An ore contains 1.24% of the mineral argentite  by mass. How many grams of this ore would have to be processed in order to obtain 1.0 g of pure solid silver ?

A. 23.15 g

B. 69.45 g

C. 92.6 g

D. 46.3 g

Answer : Option C

Explanation :

       

248 g          216 g

 (?)            1.0 g

= 1.148 g

 

           

100 g          1.24 g

 (?)            1.148 g

= 92.58 ≈ 92.6 g

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87.  Find the electric charge in coulomb of 9.0 gm of ions.

A.

B.

C.

D.

Answer : Option A

Explanation :

No of moles of = = 0.33

 No of  ions =

 Electric charge = =  Coulomb

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88.  Which of the following is not a homogeneous mixture ?

A. Smoke

B. Air

C. Brass

D. Aqueous solution of sugar

Answer : Option A

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89.  Which of the following has the largest number of atoms ?

A. 0.5 g atom of Cu

B. 0.635 g of Cu

C. 0.25 moles of Cu atom

D. 1 g of Cu

Answer : Option A

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90.   27 g of Al (at mass = 27) will react with oxygen equal to (IIT 1978)

A. 24 g

B. 8 g

C. 40 g

D. 10 g

Answer : Option A

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