is captured by a U-235 metastable   nucleus named isotopes  nucleus (is) unstable  nucleus splits  into 2 daughter nuclei (of  similar size) (2 or more) neutrons are  released energy is released  (c) An explanation linking Reverse argument moderator slows down  (absorbs energy from) neutrons (2) more likely to be captured  /cause fission (if it collides with a U-235 nuclei) Q21. Question Answer Acceptable answers Mark Number (a) D (1) Question Answer Acceptable answers Mark Number (b) An explanation linking the following points idea that • the procedure has been checked to confirm consistent results (1) (by) other reputable • scientists /organisations / peers (1) (2) Question Answer Acceptable answers Mark Number (c) A description including three of the following points hydrogen / small nuclei • (1) join or fuse (1) to • • form helium / larger nuclei (1) energy is released (1) (3) • Question Indicative Content Mark Number A description including some of QWC *(d) the following stages Fission• absorption of slow moving / thermal neutron by to produce daughter • nuclei, two or more neutrons and two or more neutrons and Controlled reaction• use of moderators to produce (6)
 is captured by a U-235 nucleus  nucleus (is) unstable  nucleus splits  into 2 daughter nuclei (of similar size)  (2 or more) neutrons are released  energy is released  metastable  named isotopes (c) An explanation linking  moderator slows down (absorbs energy from) neutrons  more likely to be captured /cause fission (if it collides with a U-235 nuclei) Reverse argument (2) Q21. Question Number Answer Acceptable answers Mark (a) D (1) Question Number Answer Acceptable answers Mark (b) An explanation linking the following points • idea that the procedure has been checked to confirm consistent results (1) • (by) other reputable scientists /organisations / peers (1) (2) Question Number Answer Acceptable answers Mark (c) A description including three of the following points • hydrogen / small nuclei (1) • join or fuse (1) • to form helium / larger nuclei (1) • energy is released (1) (3) Question Number Indicative Content Mark QWC *(d) A description including some of the following stages Fission• absorption of slow moving / thermal neutron by • to produce daughter nuclei, two or more neutrons and two or more neutrons and Controlled reaction• use of moderators to produce (6)
p2_revision_pack_mark_scheme.docx