Question 4
4
A helium nucleus contains two protons. In a model of the helium nucleus, each proton is considered to be a charged point mass. The separation of these point masses is assumed to be \(2.0 \times 10^{-15} \mathrm{~m}\).
structured5 marks
Question 4(b)
4(b)
Using your answers in (a), suggest why
structured5 marks
Question 4(b)(i)
4(b)(i)
there must be some other force between the protons in the nucleus,
Mediumstructured3 marks
Answer
force of repulsion (much) greater than force of attraction must be some other force of attraction to hold nucleus together (Do not allow if \(F_{\mathrm{G}}>F_{\mathrm{E}}\) in (a) or one of the forces not calculated in (a))
Question 4(b)(ii)
4(b)(ii)
this additional force must have a short range.
Mediumstructured2 marks
Answer
outside nucleus there is repulsion between protons either attractive force must act only in nucleus or if not short range, all nuclei would stick together
Question 38
38
Which fundamental particles form a hadron? leptons nucleons photons quarks
Easymcq1 marks
Answer
D
Question 38
38
Which flavours of quark have charge \(+\frac{2}{3} e\) ?
Mediummcq1 marks
Answer
A
Question 7
7
4 marks
Question 7(a)
7(a)
Fluorine-18 \(\left({ }_{9}^{18} \mathrm{~F}\right)\) is an isotope that decays to an isotope of oxygen ( O ) by the emission of a \(\beta^{+}\)particle.
structured1 marks
Question 7(a)(ii)
7(a)(ii)
A quark in the fluorine-18 nucleus changes flavour during the decay. State this change of flavour. quark to quark.
Hardstructured1 marks
Answer
up quark to down quark B1
Question 7(b)
7(b)
A hadron has a charge of -2 e, where e is the elementary charge.
structured3 marks
Question 7(b)(i)
7(b)(i)
State and explain whether the hadron is a meson or a baryon.
Mediumstructured2 marks
Answer
must be three (anti)quarks as largest (negative) quark charge is (-)2/3(e) or mesons can only have a charge of 0 or \(\pm 1(e)\) M1 (so hadron is) a baryon A1
Question 7(b)(ii)
7(b)(ii)
State a possible quark composition for the hadron.
Mediumstructured1 marks
Answer
any combination of three from: antiup (quark) / up antiquark and/or anticharm (quark) / charm antiquark and/or antitop (quark) / top antiquark B1
Question 7
7
4 marks
Question 7(c)
7(c)
Table 7.1 lists the names of three particles and possible classifications for them. Complete Table 7.1 by placing ticks \((\checkmark)\) in the boxes to indicate the classifications that apply to each particle.
Mediumstructured2 marks
Answer
neutrino classified as a lepton only and positron classified as a lepton only B1 neutron classified as a baryon and a hadron and not as a lepton B1
Question 7(d)
7(d)
The discovery of a particle with an unusual charge was an important step in the development of the theory of quarks. The particle is a hadron with a mass of \(2.19 \times 10^{-27} \mathrm{~kg}\) and a charge of +2 e, where e is the elementary charge.
structured2 marks
Question 7(d)(ii)
7(d)(ii)
Determine a possible quark composition of a hadron with a charge of +2 e. Explain your reasoning.
Hardstructured2 marks
Answer
working states or implies 3 quarks and each quark has a charge of \((+) \frac{2}{3}(e)\) B1 any combination of 3 quarks comprised of one or more of up / charm / top B1
Question 39
39
Which particle is not a fundamental particle? electron neutrino neutron top quark
Easymcq1 marks
Answer
C
Question 39
39
The diagrams show the quark composition of four different hadrons. One of the hadrons is a \(\Sigma^{+}\)particle. It has a charge of +e, where e is the elementary charge. Which hadron could be the \(\Sigma^{+}\)particle? key u = up quark d= down quark s= strange quark
Mediummcq1 marks
Answer
D
Question 39
39
What are the structures of the proton and of the neutron in terms of quarks?
Mediummcq1 marks
Answer
C
Question 40
40
A positively charged meson consists of a quark and an antiquark. What could be the quark and antiquark? charm and antiup down and antitop strange and antibottom up and antistrange
Hardmcq1 marks
Answer
D
Question 40
40
What is the charge of a top antiquark? \(-\frac{2}{3}\) \(-\frac{1}{3}\) \(+\frac{1}{3}\) \(+\frac{2}{3}\)
Easymcq1 marks
Answer
A