# IBDP Physics 7.3 – The structure of matter: IB Style Question Bank SL Paper 1

### Question

A particle reaction is Which conservation law is violated by the reaction?

A Baryon number

B Charge

C Lepton number

D Momentum

Ans: B

Considering Charge on the both sides of equation:

$$p= +1,\; \bar{e}=-1 \; \bar{\nu _\mu} =0$$
on right side
$$n= 0\; \mu^+ =+1 , \nu _e =0$$
Hence $$1-1+0 \neq 0+1+0$$
Hence Charge Conservation is violated.

### Question

Which Feynman diagram shows beta-plus (β+) decay? ## Markscheme

A

In beta-plus (β+) decay  process, a positron and a neutrino are created and emitted from the nucleus.

$$p\rightarrow n+e^{+} + \nu_e$$

we look deeper and see that a  proton (uud) can change into a neutron (udd) by changing a up quark into an down quark.We now view the fundamental beta-decay process as

$$u\rightarrow d+e^{+} + \nu_e$$ ### Question

The Feynman diagram shows a particle interaction involving a W boson. Which particles are interacting?

A. U and Y

B. W boson and Y

C. X and Y

D. U and X

## Markscheme

C

#### Neutron-neutrino Interaction When a neutron interacts with a neutrino, a W boson is released as the exchange particle, which in turn interacts with the neutrino to form the β– particle.

### Question

The reaction p+ + n0 → p+ + $$\pi$$0 does not occur because it violates the conservation law of

A.  electric charge.

B.  baryon number.

C.  lepton number.

D.  strangeness.

## Markscheme

B Baryon number of all other particle is 0

Now in given equation we have

for left side of equation
for $$p^+ , B = 1$$
for $$n^0, B =1$$
For right side of equation
for $$p^+ , B = 1$$
for $$\pi^0$$
Hence $$1+1 \neq 1+0$$

### Question

As quarks separate from each other within a hadron, the interaction between them becomes larger. What is the nature of this interaction?

A. Electrostatic
B. Gravitational
C. Strong nuclear
D. Weak nuclear