How many moles of helium gas occupy 22.4 L at 0 degree at 1atm pressure ?

1 ) How many moles of helium gas occupy 22.4 L  at  0 degree  at 1atm pressure ?

A ) 1 mol  ,                                               B ) 2 mol  ,

C ) 3 mol  ,                                               D ) None of these ,

Correct Answer : -  A ) 1 mol  ,     

Solution : -

Formula : -

Moles = volume / STP   =  22.4 / 22.4  =  1 mol  .

 

2 ) Work is not a state function .

 

3 ) Each carbon in benzene is ……… hybridized .

A ) sp1 ,                                           B ) sp2 ,

C ) sp3 ,                                           D ) None of these ,

Correct Answer : -  B ) sp2 ,

 

4 ) ( Mass spectrometer ) …………… is used to measure the mass of a charge particle .

 

5 ) Percentage of calcium in calcium carbonate  is ?

A ) 20 % ,                                        B ) 40 % ,

C ) 80 % ,                                                D ) None of these ,

Correct Answer : -  B ) 40 % ,

Solution : -

Ca = 40  ,  C = 12  , O = 16  ,

So , 

Ca/(CaCO3) x 100  =  40/(40+12+48) x 100 = 40/100 x 100 = 40 %

Answer .

 

6 ) No. of molecules formula : -

No. of molecules = ( mass / molar mass ) x N_A  ,

 

7 ) Ionic compounds are …………..  in solvent that contains a common ion .

A ) less soluble ,                                      B ) more soluble ,

C ) are un soluble ,                          D ) None of these ,

Correct Answer : -  A ) less soluble ,

 

8 ) An X grams of calcium carbonate was completely burnt in air . The weight of solid residue formed is 28 g .  What value of X grams ?

A ) 25 g ,                                          B ) 50 g ,

C ) 100 g ,                                               D ) None of these ,

Correct Answer : -  B ) 50 g ,

Solution : -

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