Question

Q. Suppose the elements A and B combine to form two compound AB and A2B. When 0.1 mole of AB weighs 20 g and 0.5 mole of A2B weighs 125 g. The atomic weight of A and B respectively are
(a) 100 and 150
(b) 75 and 50
(c) 50 and 150
(d) 80 and 140

Best one will be marked as brainlist

Answer 1

Answer:

moles=

molarmass

mass

then, molarmass=

moles

mass

B

2

A

3

molar mass =90.05=180

relative formula mass of B

2

A

3

=180

that means,

(atomic mass of A) ×3+ (atomic mass of B) 2=180

3A+2B=180.....(i)

B

2

A molar mass =

0.1

10

=100u

2B+A=100.....(ii)

from equation (i) and (ii)

A=40

B=30

Hence, the correct option is B

Answer 2

Step-by-step explanation:

moles=

molarmass

mass

then, molarmass=

moles

mass

B

2

A

3

molar mass =90.05=180

relative formula mass of B

2

A

3

=180

that means,

(atomic mass of A) ×3+ (atomic mass of B) 2=180

3A+2B=180.....(i)

B

2

A molar mass =

0.1

10

=100u

2B+A=100.....(ii)

from equation (i) and (ii)

A=40

B=30

Hence, the correct option is B