Question

Drag the correct symbol to the equation. Not all symbols will be used.

A plutonium atom undergoes nuclear fission. Identify the missing element in the nuclear equation.
239Pu + 1n ---> ____ + 134Xe + 3 1n
94 0 54 0

Options:
101Zr
40

134Xe
54

105Zr
40

103Zr
40

102Xe
54

Answer 1

Correct Answer is 103

40 Zr

Step-by-step explanation:

Took the Test and got it right :)

Answer 2

• ¹⁰³₄₀ Zr

Step-by-step explanation:

The nuclear equation from which you have to identify the missing element is:

• ²³⁹₉₄ Pu + ¹₀n → ___ + ¹³⁴₅₄Xe + 3 ¹₀n

The superscripts to the left of each chemical symbol are the mass number of the atoms (number of protons plus neutrons) and the subscripts to the left of the chemical symbols are the atomic numbers of the atoms (number of protons).

Thus, such equation must be read as "an atom of plutonium-239 is bombarded with a neutron and produces one atom of an unkwon element, one atom of xenon-134, and 3 neutrons".

To find the identity of the missing element you must do two balances: mass number and atomic number.

Mass number:

• 239 + 1 = A + 134 + 3×1

• A = 240 - 134 - 3 = 103

Hence, the mass number of the missing element is 103.

Atomic number:

• 94 + 0 = Z + 54 + 3×0

• Z = 94 - 54 = 40

Hence, the atomic number of the missing element is 40.

In a periodic table you can find that the element with atomic number 40 is zirconium, Zr.

Thus, the identity of the missing isotope is zirconium-103, ¹⁰³₄₀Zr.

And the complete equation is:

• ²³⁹₉₄ Pu + ¹₀n → ¹⁰³₄₀ Zr + ¹³⁴₅₄Xe + 3 ¹₀n