Question

5. If Z = 20 and A = 40 for an unknown element X and the no.of neutrons in = X another element Y (Z = 18) is morethan 2 in X. The mass no.of Y is A) 20 B) 38 C40 40 D) 18​

Answer 1

Answer:

6 2N2O5→4NO2+O2 <br> Calculate the average rate of this reaction in terms of hours, minutes, and seconds. What is the rate of Production of NO2 during this period?

6 2N2O5→4NO2+O2 <br> Calculate the average rate of this reaction in terms of hours, minutes, and seconds. What is the rate of Production of NO2 during this period?141186187

6 2N2O5→4NO2+O2 <br> Calculate the average rate of this reaction in terms of hours, minutes, and seconds. What is the rate of Production of NO2 during this period?1411861870

6 2N2O5→4NO2+O2 <br> Calculate the average rate of this reaction in terms of hours, minutes, and seconds. What is the rate of Production of NO2 during this period?1411861870900

Answer 2

Answer: Option C

Given:

Z = 18 for Y

Z = 20 for X

A = 40 for X

To find:

The mass number of Y (A).

Solution:

we know , Z = atomic number

A = mass number

X, Y = elements

no. of neutrons (n) = (A-Z)

n = (40-20) for element X

= 20 for element X

n = (n of element X + 2) for element Y

= 22

A = (n of element Y + Z of element Y)

= 22+ 18

= 40 for element Y

Therefore, The mass number of Y is 40 (option C)