Question

The half Life period of a reaction is 100 min. In 400 minutes the initial concentration of 2.0 g will become--
A)0.25g
B)0.75g
C)0.125g
D)0.1g


Plz answer....​

Answer 1

Answer:

C) 0.125g

Explanation:

no.of half-lives = n = 400/100 = 4

Nt = ( No/2^n)

=( 2/2^4)

= 0.125g

Answer 2

In 400 minutes the initial concentration of 2.0 g will become (c) 0.125 g.

Given: The half-life period of a reaction is 100 min

To Find: In 400 minutes the initial concentration of 2.0 g will become,

Solution:

• It is to be noted that amount of substance is calculated using,

     Amount of substance = A / 2^( number of half-life periods)   ....(1)

where A = initial concentration.

Coming to the numerical, we have;

 In 100 min, the  number of half-life periods = 1

 In 1 min, the  number of half-life periods = 1 / 100

∴in 400 min, the number of half-life periods = 400 / 100

                                                                             = 4

Initial concentration (A) = 2 g

Number of half-life periods = 4

Now, putting respective values in (1), we get;

Amount of substance = A / 2^( number of half-life periods)

                                     = 2 / ( 2^4)  g

                                     = 0.125 g

Hence, in 400 minutes the initial concentration of 2.0 g will become  (c) 0.125 g.

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