Question

The total number of electrons present in 3.2g of methane are:

a)2 x 10 x 6022x10^23

b) 10 X 6.022 X 10^23

c) 10X 6.022 X10^22

(d) 6.022 x 10^23​

Answer 1

The total number of electrons present in 3.2g of methane are:

a)2 x 10 x 6022x10^23

b) 10 X 6.022 X 10^23

c) 10X 6.022 X10^22

(d) 6.022 x 10^23

explanation :

Mass= 1.6gm

Moles=

16

1.6

=0.1

Total number of molecules= 6.027×10

23

×0.1=6.023×10

22

Electron in 1 molecule= C+H×4⇒6+4=10

So in, 6.023×10

22

molecules ⇒10×6.023×10

22

⇒6.023×10

23

Answer 2

Corrected question:

The total no. of electrons in 3.2g of methane are:

a)2 x 10 x 6.022x10^22 (corrected option)

b) 10 X 6.022 X 10^23

c) 10X 6.022 X10^22

(d) 6.022 x 10^23​

Answer:

The total number of electrons in 3.2g of methane is 2×10×6.022×10^22 electrons. (option a)

Given,

The mass of the methane = 3.2g

To find,

Total number of electrons

Solution,

This question can easily be done using the unitary method.

We know the molecular mass of methane ($CH_4$) is 16g.

So the number of moles of $CH_4$ = 3.2/16

                                                     = 0.2 moles

Thus, the number of molecules present = 0.2 × 6.022×$10^{23$

1 molecule of $CH_4$ has 10 electrons. (C -> 6, H -> 4)

∴ 0.2 × 6.022×$10^{23$ molecules of $CH_4$ will have 0.2 × 10 ×6.022×$10^{23$ $e^-s$

                                                    =  2 × 10 ×6.022×$10^{22$ electrons.

∴ There are 2×10×6.022×10^23 electrons in 3.2g of methane. (option a)

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