1 ) How much does 22.4 liters of oxygen weigh at STP ?
A ) 18 g , B
) 26 g ,
C ) 32 g , D
) None of these ,
Correct
Answer : - C ) 32 g ,
Solution
: -
Volume = moles x STP ,
So , moles = volume / STP ,
So , moles = 22.4 / 22.4
= 1 .
So we use 2nd formula here to find mass : -
moles = mass / molecular mass ,
mass = molecular mass x moles
,
mass = 32 x 1,
mass
= 32 g
, Answer .
2 )
One litre oxygen gas at STP will weight : -
A ) 0.18 g , B
) 1.43 g ,
C ) 3.29 g , D
) None of these ,
Correct
Answer : - B ) 1.43 g ,
Solution
: -
Volume = moles x STP .
So , moles = volume / STP ,
So , moles = 1 / 22.4 .
So we use 2nd formula here to find mass : -
moles = mass / molecular mass ,
mass = molecular mass x moles
,
mass = 32 x ( 1 / 22.4
) ,
mass
= 1.43 g , Answer .
3 )
The mass of one mole of electron is ?
Solution
: -
mass of electron = 9.11 x 10 ^ ( - 31 ) kg .
1 mole = NA = 6.022 x 10 ^ 23 .
NA = Avagodras number .
So , formula for finding moles : -
mole = mass x NA ,
1 mole of electron = 9.11 x 10 ^ ( - 31 ) x 6.022 x 10 ^
23 ,
1 mole of electron = 54.86 x 10 ^ ( - 5 ) ,
Answer
4 )
An aqueous solution of glucose is 10 % in strength . The volume in which 1 g mole of it is dissolved will be : -
Solution
: -
10 % means if we take 10 g glucose = ( 10 / 180 ) mole glucose will present in 0.1 L solution
or 100 cc .
So , ( 10 / 180 ) mole ---------> 0.1 L ,
1 g mole = ( 0.1 x 180 L ) / 10 = 1.8 L .
OR
Now go to online quiz section and Chemistry Quiz 5 is uploaded related to these mcqs , so check your preparation by this link : -
