##### Admin

**In the reaction above, X is**

**A. electron.**

**B. neutron.**

**C. neutrino.**

**D. proton.**

**QUICK ANSWER…**

**B**

**DETAILS…**

**The sum of the mass numbers on the right-hand side = that on the left-hand side**

**Also, the sum of the atomic numbers on the right-hand side = that on the left-hand side.**

**Sum of mass numbers on the left-hand side = 235 + 1 = 236**

**Hence, 236 = 144 + 90 + 2X**

**So, the mass number of 2X = 236 – 144 – 90 = 2**

**Therefore, mass number of X = 2/2 = 1**

**Also, sum of atomic numbers on the left-hand side = 92 + 0 = 92**

**Hence, 92 = 56 + 36 + 2X**

**2X = 92 – 56 – 36**

**2X = 0**

**X = 0**

**This means X = 1 mass number, and 0 atomic number**

**X = neutron.**

**Now for the right answer to the above question:**

**Option A is incorrect. electron would have 0 mass number and -1 atomic number.****Option B is correct. neutron have these features.****C is incorrect. neutrinos are special kind of sub-atomic particles with almost zero mass, they are seldom represented in nuclear equations.****D is not the correct answer. A proton would have 1 mass number and 1 atomic number.**

**KEY-POINTS…**

**You may please note these/this:**

**Neutrons are not the same as neutrinos.****Neutrons have a notation in small letter n, with subscript as 0 and superscript as 1.**

**Use the questions and answers session to raise further questions and deal more on this topic…**

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**/ culled from 2016 JAMB-UTME physics past question 14 /**

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