(a) Balance the nuclear equation below and hence identify Y. \(^{238}_{234}U \to ^{234}_{92}Th + Y\) (b) In.a tabular form, state two of the observations in...
Question 1 Report
(a) Balance the nuclear equation below and hence identify Y.
\(^{238}_{234}U \to ^{234}_{92}Th + Y\)
(b) In.a tabular form, state two of the observations in the cathode ray experiment and the corresponding deductions.
Answer Details
(a) Balancing the nuclear equation
\[^{238}_{92}U \to\ ^{234}_{90}Th + Y\]Balancing the mass numbers: \(238 = 234 + A \Rightarrow A = 4\).
Balancing the atomic numbers: \(92 = 90 + Z \Rightarrow Z = 2\).
So \(Y\) has mass number 4 and atomic number 2, i.e. \(^{4}_{2}He\). Y is an alpha particle (a helium nucleus), and the process is alpha decay:
\[^{238}_{92}U \to\ ^{234}_{90}Th +\ ^{4}_{2}He\](b) Cathode-ray experiment: observations and deductions
| Observation | Deduction |
|---|---|
| The rays travel in straight lines and cast a sharp shadow of an object placed in their path | Cathode rays are made of fast-moving material particles |
| The rays are deflected towards the positive plate in an electric (or magnetic) field | The particles carry a negative charge (they are electrons) |
(A further acceptable pair: the rays turn a small paddle wheel placed in their path, showing the particles have mass and momentum.)
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