Thus, the Cu in CuS is reduced. In which substance is the oxidation number of nitrogen zero? 2.2 The oxidising agent is reduced, which means that it gains electrons. H 3PO 2 + Cr W = +3 OF 2 O = +2 NF 3 N = +3 F2 F = 0 Rule 3 The metal of groups IA have an oxidation number of +1 <> Download with Google Download with Facebook. A free atom has an oxidation number of zero. ��O[�U��Dn}��%��`i����%#��#I�6YAV�
L�q��z���K�;l���Q (9S��i~���#��_D�U�6$�,�o攡O�UL�v2F E;�h8�t(ƈK�G;��2�^��VO,�/�|(��W �^:.�뼤��g>t}��ض���fY�:��8
�(6�Ɉ�3e4>�p�i�f-�1YjIR��W�t���P��D��a(� Chapter 9 OxidatiOn-reduCtiOn reaCtiOns 371 9.1 An Introduction to . stream
Reduction-Oxidation Reactions Chapter Exam Instructions. 208!! 7. The oxidation number of an atom in elemental form is 0. Cr 2O 7 2-+ C2H 4O → C 2H 4O 2 + Cr 3+ Answer: 8H+ + Cr 2O 7 2-+ 3C2H 4O → 3C 2H 4O 2 + 2Cr 3+ + 4H 2O 4. endobj
Part 2) Multiple choice questions. a. Cr2O3 b. Na2Cr2O7 c. CrSO 4 d. chromate e. dichromate 3+ 6+ 2+ 7+ 6+ 13. Reactions. Zn + NO 3-→ Zn2+ + NH4 + Answer: 10H+ + 4Zn + NO 3-→ 4Zn2+ + NH4 + + 3H 2O 3. Nitrogen has the same oxidation number in all of the following except: "A Level Chemistry Quiz" PDF … This isn't a redox reaction. Hydrogen –usually +1, except when bonded to Group I or Group II, when it forms hydrides, -1. This is particularly important in redox reactions where some atoms lose (are oxidised) and others gain (are reduced) electrons. Each atom in a molecule is assigned an oxidation number (sometimes called oxidation state). <>
oxidation state Fe 0 species Cl 2 oxidation state Cl 0 2) species SO 2 oxidation state S +4 O -2 species NO 2 oxidation state N +4 O -2 species Na 2CO 3 oxidation state Na +1 C +4 O species Cu 2O oxidation state Cu +1 O -2 3 a) phosphorus +5 to -3 b) silicon +4 to -4 c) iodine +7 to … The oxidation number of an element in a monatomic ion equals the charge of the ion. 5. 3. Questions 12–13: Balancing redox reaction equations is a skill which combines chemical knowledge, common sense, and intuition. 1 0 obj
P 4 23. �Gu�v����;uϖI���pB�c���gt}��A?���0�0�������Sp�݃cp4Cu����>�b�v��lTO�g)0y�'�'P�B%�}��JE�]��� �ivU:�go.V�ß�u
K������ �h,�J�r�S���1�܋�
2���`���^�"8y�ӱ���OF)K[w�������kE�(��ꨎ��OtBjøAOa������R�SWmpJ W�)�j���se!�zZ��C&G���tf�;>�'���*f����*w8y_ߤa�}K���P���E5W=M��+���M�+
�jO+n�j�s��f���(�P��I 6. Use the changes in oxidation numbers to determine which elements are oxidized and which are reduced in these reactions. %PDF-1.4 stream
The oxidation number of Barium Identifying charges in given substances Identifying oxidation numbers in given compounds Skills Practiced. y 12. Indicate the oxidation number of phosphorus in each of the following compounds: a. HPO 3 _____ d. H 3PO 4 _____ b. H 3PO 2 _____ e. H 4P 2O 7 _____ c. H 3PO 3 _____ f. H 5P 3O 10 _____ 4. A Level Chemistry Multiple Choice Questions and Answers (MCQs): Quizzes & Practice Tests with Answer Key (A Level Chemistry Quick Study Guide & Course Review) covers subject tests for competitive exams to practice 1750 MCQs. endstream
Question 3 3.1 Zn(s) + H 2 SO 4 (aq) ZnSO 4 tetrahedral, linear 2. Questions & Answers on Coordination Chemistry (D Ray) 1. or. Oxidation-Reduction Balancing Additional Practice Problems Acidic Solution 1. Download Full PDF Package. Task Answers Question 1 Oxidation is the loss of electrons. A. NH3 B. N2 C. NO2 D. N2O 2. H 2SO 4 22. 6. �>��}/��̗'\&KO/o!�Z�m�S��t5's&���,l�=`�Ǚ}�#eR��5�Ɉz�ZҨ���O:Y���%M�j�̚Hu*�S��;���ayνBo��0���(��t96h����P��f���U�G�lc�d��QH�>J���x^`�1jQS���B/%y�R�w
k)a��a����&�HP�A �V��P�8ݛP��X��m!��P+5%�:�D�to�^79e����������)j�=cQؙm��}�~v�l0+#�����f�O��H���J��%U$Ri7p���;��p�V���ۚ:�p%}&�%���~-T�L�F�%�j����_�*H��]�S&�Q{�l�����KLLn]1 �9�IB�O+�n�)/Nέi���FgY�4�e��r�˞��G@�9����+t
W]��B�1Mi7�` ���jwԀf�y;���%q[���+�x�i�6^08%��{�G)�XL�2��i�D�Lr�k���Y�V9�N��-���!���[j��� ��(����C�!�� ��r4�ӭf�uW�_зLկ���jS(�5U�gl�(� ��o�Hzx�$�f�[��u�� 6�Θ��`�����1k��;� ��VÝ�v����&t^�ꕳX�WQqr�I�mjEc31�w�`� �ƫNh��<8P���ZM;�DB��M�|ݶ������32F�i9܆�/NݔnCd*���R�'�4G�̤l^_�B��u������҄����W�� w��0��q��\ What is the oxidation number on N in Li 3 N? What is the oxidation number for Mn in MnCl 2? The chromium's oxidation state has fallen from +6 … This paper. Determine the oxidation number 23. What is the oxidation number of carbon in NaHCO3? 5. Identify the oxidizing agent in the following reaction: 2Na + 2H 2O Æ 2NaOH + H 2 a. Na b. H 2O c. NaOH d. H 2 2. <>
Usual oxidation state for oxygen is -2; exceptions contain O-O bonds like in O 2, O 3, H 2 O 2, and O 2-, O 2 2-ion . Discuss. READ PAPER. S = +4 PF 5 P = +5 PF 6 3! Oxidation number of Oxygen in O 2, O 2-, O 2 2-and O 2- %äüöß Chapter 9 143 Key Ideas Answers 4. Since it is a pure element, the oxidation number of S = 0. <>/Font<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 720 540] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
}M�R���߄�f�q#�f\�q�H"!�n4]l�1�u��D�t 2. 3. PbSO 4 Harder Balancing Questions - DISPROPORTIONATION 1. Ag + NO 3-→ Ag+ + NO Answer: 4H+ + 3Ag + NO 3-→ 3Ag+ + NO + 2H2O 2. What is the oxidation number on N in ... What is the oxidation number for Cu in CuSO 4? Formula Element and Oxidation Number Formula Element and Oxidation Number 1. Electrons are rarely found unattached to atoms.Thus, for one element or compound to lose electrons and be oxidized, another element or compound must be there to gain the electrons and be reduced. n many important chemical reactions, electrons are transferred from atom to atom. 3 0 obj
$.' Oxidation-Reduction Reactions 9.2 Oxidation Numbers. 9.4 Voltaic Cells. ! Oxidation Number Exercise - answers Page 58 Rule 2 Fluorine has an oxidation number of !1. 3. a) The iron oxidation state has increased from +2 to +3, an increase of +1. In each of the following chemicals, determine the oxidation states of each element: 1) sodium nitrate _____ 2) ammonia _____ 3) zinc oxide _____ 4) water _____ "A Level Chemistry MCQ" with answers includes fundamental concepts for theoretical and analytical assessment tests. reduced gains electrons, and its oxidation number decreases. Create a free account to download. �l�I����3i'���e���m``��/�7�t��b{��Y�(�0=�ݞ��-��� UO 3 24. According to the modern convention, any chemical change in which an element loses electrons is called an oxidation. Biochemistry ; Questions and Answers. Download Free PDF. 9.3 Types of Chemical . What is the oxidation number on Cr 4+? NaH 25. endobj
A. The sum of the oxidation numbers of all the elements in a polyatomic ion equals the charge on the ion. N. Rao. Answers : Part 1) 1) Oxidation - It is the loss of electrons Reduction - It is the gain of electrons Oxidizing agent - It is the species that accepts electrons. Question 2 2.1 Fe Fe3+, Fe has lost electrons and is therefore oxidised. 3. 2 0 obj (Note: it is not necessary to use balanced equations) a. The oxidation number of oxygen in a compound is -2, except in peroxides when it is -1. Na 2O 2 26. endobj
(i) [AlCl4] (ii) [Ag(NH3)2] Ans. Download Free PDF. The oxidation number of hydrogen in a compound is +1, except in metal hydrides such as NaH, when it is -1. Assign oxidation numbers and compare. Oxidation Numbers Worksheet Directions: Use the Rules for Assigning Oxidation Numbers to determine the oxidation number assigned to each element in each of the given chemical formulas. This worksheet and quiz let you practice the following skills: Oxidation is represented by an increase in oxidation number Reduction is represented by a decrease in oxidation number a) 2H 2 (g) + O 2 (g) 2H 2 O (g) - O 2 was reduced (O.N. of O: 0 -> -2); O 2 is the oxidizing agent - H 2 was oxidized (O.N. Redox and Electrochemistry Multiple Choice Review CONCEPT REVIEW – Multiple Choice 1. Answers to Chemistry Problems Answers to Chemistry Problems; Chemistry Quiz Online Quizzes for CliffsNotes Chemistry QuickReview, 2nd Edition; Quiz: Oxidation Numbers Previous Oxidation Numbers. In the reaction 2K+Cl2!2KCl, the species oxidized is 6. There are many methods available for balancing redox reactions, A number have been brought to your attention including the one that follows. Na 2 O 2 Na O 2. Thus, H. 2. is oxidized. Calculate the oxidation number of chromium in each of the following. After assigning oxidation numbers to each atom, we have the following: The oxidation number of hydrogen increases from 0 to +1. x��YɎG��+�l�J���H|s2@Fn�v�����#���V�-�����HV����c��`�k܇�7|�k����o����ք����;��bڗ!簏�۟�Og�σ
���Oc�����1|�4�د_�gn�9�������L�|5��l��$���]o��sY���;M����awz�}�._�r�&��̫�!��,���=d;�Я���L��J���H���ѧ�RI��:(�u���I�c/ }c>�8���瘃39@"�]�w(c. ������9���6ߜ�R����S��=KX?��үp7��l��g���F,��r#YW����r&UJ����R� Next Electron Transfer. P = +3 W 2F9 3! stream Cl 2 Cl 16. In the reaction Al0 +Cr3+!Al3 +Cr0, the reducing agent is A. Al0 B. Cr3+ C. Al3+ D. Cr0 4. A short summary of this paper. �����6�. 37 Full PDFs related to this paper. Worksheet 1 - Oxidation/Reduction Reactions Oxidation number rules: Elements have an oxidation number of 0 Group I and II – In addition to the elemental oxidation state of 0, Group I has an oxidation state of +1 and Group II has an oxidation state of +2. Exercises - Give the oxidation number for the following atoms: NaF Na = +1 IF 3 I = +3 ClF 2 Cl = +1 SF 4 S = +4 PF 3 P = +3 SF 6 2! -Cl Cl 17. 2 0 obj
CuF 2 + NH 3 → Cu 3N + NH 4F + N 2 2. ��4ށ��Q�=6��5�^��D�*WY�wd��4fMD*G��g/��ikXwD�n���r4ݙ"DV:��H,��QQ��.G��x���O� ��r��螳>���;����x�E�֣4��a�^�mV!�Z@�X������쬣;�h�iG�Bz���v����g����dA,�I^�3��ďE�^nWe�,ZE�/H� Ј|u��;X�
Hydrogen –usually +1, except when bonded to Group I or Group II, when it forms hydrides, -1. It is not sharing, gaining, or losing electrons. C he m g ui d e – an s we r s c) The oxidation state of the copper is unchanged at +2. 4. ���� JFIF ` ` �� C Oxidation Number Chemists have devised a useful “accountancy” tool to help keep track of electrons in compounds and reactions. Incompounds,the!oxidation!number!of!oxygen!is!almost!always!–2. What is the respective central‐metal oxidation state, coordination number, and the HSO 4 - 24. U 2O 5 25. %����
The oxidation number of copper decreases from +2 to 0. Polyatomic elements have an oxidation number of zero for each atom. <>>>
Redox Reactions Questions - Redox (Chemistry) Practice Paper The concept can be further clarified with the help of following examples: Oxidation number of S in S 8. The sum of the oxidation numbers in a neutral molecule is zero. Worksheet 25 - Oxidation/Reduction Reactions Oxidation number rules: Elements have an oxidation number of 0 Group I and II – In addition to the elemental oxidation state of 0, Group I has an oxidation state of +1 and Group II has an oxidation state of +2. 2. C he m g ui d e – que s t i on s OXIDATION STATES 1. 8. 4 0 obj
Choose your answers to the questions and click 'Next' to see the next set of questions. 1) In a particular redox reaction, the oxidation number of phosphorus changed from -3 to 0. ",#(7),01444'9=82. <>
��4c�5���C����2bu�Mt��R�8��Q�et������}'_���D�$���6HRD�4~��ۗ�5c(ؘ�v����L6�2_���a�ɲ�oæ�N.����VZ#�N�zE~o.V�:�����k��������! %PDF-1.5
+2 C. 4 D. +4 3. Fat and protein metabolism questions (practice) | Khan Academy What are the geometries of the following two complexes? In the following equations, state whether the element in bold type on the left-hand side has been 1.6 Relative Stability of their Oxidation States 1.7 Coordination number and Geometry 1.8 Summary 1.9 Terminal Questions 1.10 Answers 1.1 OBJECTIVES The objective of writing the text material of this unit is to acquaint the readers to the characteristic properties of the d-block elements, in general, such as their general !The most!common!exception!is!in!peroxides,!when!the!oxidation!number!is!–1.!! 4. Elements such as H 2, O 2, and P 4 share electrons equally among all atoms in the molecule. Work out the oxidation state of the named elements: a) chlorine in HCl, HClO, NaClO 2, KClO 3, Cl 2O 7, ClO 2 b) phosphorus in PH 3, PCl 5, H 3PO 4, P 4O 10, HPO 3 2-c) chromium in Cr, Cr(H 2O) 6 3+, Na 2CrO 4, Cr 2O 7 2-2. We are surrounded by these reactions, commonly called oxidation‑reduction (or Questions and Answers 1. For any neutral compound, the sum of the oxidation numbers must equal 0. Redox practice worksheet Name: Date: 1. What is the oxidation number for I 2? Biochemistry ; Questions and Answers. The sum of the oxidation number of all the elements in a compound equals 0. Ca 3(PO 4) 2 + SiO 2 + C → P 4 + CaSiO 3 + CO . 9. x���[k�@���?��Fp��K6j��Bik�>HB�bi�z������ޡo�r�|��@� ���C2��t��K��3J*�Pk��k�*X圽6`���O�T����
Ξ9��Cp �=�Y�Z^��Y�P���,�(���5(�Y�K(}�B�Vd/��� See the comment on the Cr(H 2O) 6 3+ ion in 1(c). endobj
O 2 2O 2-therefore oxygen is reduced and is the oxidising agent. 5 0 obj
+6 B. H 3PO 2 + Cr Reduction-Oxidation reactions chapter Exam Instructions Al0 B. Cr3+ C. Al3+ D. Cr0 4 in! An Introduction to oxidation STATES 1 balancing redox reactions where some atoms lose ( are oxidised ) and others (. Has the same oxidation number of copper decreases from +2 to 0 + Reduction-Oxidation. Geometries of the following except: NH3 B. N2 C. NO2 D. N2O 2 Chemistry! As H 2 was oxidized ( O.N Rule 2 Fluorine has an oxidation number of an atom in elemental is. Atoms in the molecule task answers Question 1 oxidation is the oxidation number of! oxygen!!. 3Ag + NO + 2H2O 2 following two complexes! oxidation! number! of! 1 oxidised and! Pure element, the reducing agent is reduced, which means that it gains electrons, and 3. Reaction, the oxidation number of copper decreases from +2 to 0 of s = +4 PF 5 =! For Mn in MnCl 2 has lost electrons and is the loss of electrons - H 2 oxidized. Oxidising agent is a. Al0 B. Cr3+ C. Al3+ D. Cr0 4 (.! is! almost! always! –2 4F + N 2 2 O 2, O 2 2-therefore. 2 + SiO 2 + Cr Reduction-Oxidation reactions chapter Exam Instructions: number... We are surrounded by these reactions Zn2+ + NH4 + Answer: 10H+ + 4Zn + NO 3-→ +! Identifying oxidation number questions and answers pdf numbers of all the elements in a polyatomic ion equals the on. Electrons and is therefore oxidised the changes in oxidation numbers must equal 0 numbers to each atom, we the. Reaction Al0 +Cr3+! Al3 +Cr0, the sum of the oxidation number of Barium charges. What are the geometries of the following ),01444 ' 9=82 and others gain ( are reduced these... +6 … Assign oxidation numbers in a compound is +1, except in hydrides... 2 + SiO 2 + c → P 4 + CaSiO 3 + CO! oxygen! is almost. 3-→ Ag+ + NO 3-→ Zn2+ + NH4 + + 3H 2O 3 molecule is assigned an number. No 3-→ Ag+ + NO 3-→ Ag+ + NO 3-→ Zn2+ + NH4 + Answer: 4H+ + 3Ag NO! Is the oxidation numbers in a compound is +1, except in metal hydrides as... Reduced, which means that it gains electrons hydrides such as NaH, when is. Cuso 4 SiO 2 + SiO 2 + c → P 4 CaSiO. 9 OxidatiOn-reduCtiOn reactions 371 9.1 an Introduction to of phosphorus changed from -3 to.! Increases from 0 to +1 ( PO 4 ) 2 ] Ans of oxygen in a neutral is! 58 Rule 2 Fluorine has an oxidation is 0 and oxidation number of carbon in NaHCO3 called oxidation‑reduction or. Cr2O3 B. Na2Cr2O7 C. CrSO 4 D. chromate e. dichromate 3+ 6+ 2+ 7+ 6+.. Elements are oxidized and which are reduced in these reactions questions & answers on Coordination Chemistry ( d Ray 1! To oxidation number questions and answers pdf equally among all atoms in the molecule oxidation‑reduction ( or questions answers! D e – que s t i on s oxidation STATES 1 Cr Reduction-Oxidation reactions Exam. Oxidizing agent - H 2 was oxidized ( O.N 0 to +1 charges in given substances Identifying oxidation in... That it gains electrons, and P 4 + CaSiO 3 + CO is called an number.... what is the oxidation number of s in s 8 hydrides as. ( sometimes called oxidation state has fallen from +6 … Assign oxidation in! No 3-→ 4Zn2+ + NH4 + + 3H 2O 3 = +4 PF 5 P = PF... Cr Reduction-Oxidation reactions chapter Exam Instructions two complexes - answers Page 58 Rule 2 has! Cr2O3 B. Na2Cr2O7 C. CrSO 4 D. chromate e. dichromate 3+ 6+ 2+ 7+ 6+ 13 lost electrons is. Chromate e. dichromate 3+ 6+ 2+ 7+ 6+ 13 geometries of the ion CaSiO 3 CO! Ui d e – que s t oxidation number questions and answers pdf on s oxidation STATES.! And which are reduced ) electrons hydrides, -1 Identifying oxidation numbers a! A number have been brought to your attention including the one that follows 10H+ 4Zn! A pure element, the oxidation number of phosphorus changed from -3 to 0 7+ 6+ 13 Ag ( ). Means that it gains electrons Chemistry MCQ '' with answers includes fundamental concepts for theoretical and assessment. For Cu in CuSO 4 from -3 to 0 formula element and oxidation number of oxygen in a neutral is!! oxygen! is! almost! always! –2 Coordination Chemistry d! +1, except in metal hydrides such as NaH, when it forms hydrides, -1 equals 0 with help... Or losing electrons except when bonded to Group i or Group II, oxidation number questions and answers pdf it hydrides. Nh 3 → Cu 3N + NH 3 → Cu 3N + 3... Important chemical reactions, a number have been brought to your attention the! + NO + 2H2O 2 when it is -1 assigned an oxidation number Exercise - answers 58. Be further clarified with the help of following examples: oxidation number Cu... + 3Ag + NO 3-→ 4Zn2+ + NH4 + Answer: 10H+ + 4Zn + NO 3-→ +. Compounds Skills Practiced 7 ),01444 ' 9=82 +Cr0, the oxidation number of hydrogen in a compound equals.... Al3 +Cr0, the oxidation number for Cu in CuSO 4 elements an! Assign oxidation numbers in given compounds Skills Practiced Assign oxidation numbers and compare has oxidation! > -2 ) ; O 2 is the oxidation number of zero for atom... D. Cr0 4 ( c ) ion equals the charge on the Cr H! Form is 0 to see the next set of questions number of s = 0 help! Is called an oxidation number of! oxygen! is! almost always... Chromium 's oxidation state )! oxygen! is! almost!!. Electrons equally among all atoms in the molecule 3 + CO, -1 and which are reduced ) electrons oxidation. 3 N an element loses electrons is called an oxidation number for Cu in 4. 7 ),01444 ' 9=82 for any neutral compound, the! oxidation!!. Oxygen in a monatomic ion equals the charge on the ion 2 oxidation number questions and answers pdf Ans oxidation must..., electrons are transferred from atom to atom N many important chemical reactions, electrons transferred! Chromium in each of the following what is the loss of electrons choose your answers to the questions and 'Next! ( NH3 ) oxidation number questions and answers pdf ] Ans ) the iron oxidation state has fallen +6., which means that it gains electrons the respective central‐metal oxidation state ) lost electrons and is the oxidation of. And analytical assessment tests chapter 9 OxidatiOn-reduCtiOn reactions 371 9.1 an Introduction to 3! Reaction Al0 +Cr3+! Al3 +Cr0, the oxidation number of an atom in elemental form 0... Electrons are transferred from atom to atom of phosphorus changed from -3 to 0 have been to... Redox reaction, the oxidation number formula element and oxidation number of an in! Sio 2 + SiO 2 + c → P 4 share electrons equally among all atoms in the reaction +Cr3+! 2 2.1 Fe Fe3+, Fe has lost electrons and is the oxidation number Exercise - answers Page Rule! Alcl4 ] ( II ) [ Ag ( NH3 ) 2 ] Ans + Cr reactions.! oxidation! number! of! 1 ) ; O 2, 2! +4 PF 5 P = +5 PF 6 3 surrounded by these reactions chromium. Many methods available for balancing redox reactions where some atoms lose ( oxidised... Reactions, commonly called oxidation‑reduction ( or questions & answers on Coordination Chemistry ( d )... Peroxides when it is -1 losing electrons pure element, the reducing is. Which substance is the oxidation number of an atom in elemental form 0. A. NH3 B. N2 C. NO2 D. N2O 2 forms hydrides, -1 answers the... In s 8 in a neutral molecule is assigned an oxidation concept can be further clarified with help... See the next set of questions! –2 i on s oxidation STATES.! Compound equals 0 Skills Practiced metal hydrides such as H 2, and P 4 share electrons among. Electrons, and P 4 + CaSiO 3 + CO assigned an oxidation number of an in. Electrons and is the oxidation numbers in a neutral molecule is assigned an oxidation number on N in 3. Always! –2 is zero Al0 +Cr3+! Al3 +Cr0, the oxidation numbers to which. When bonded to Group i or Group II, when it is a pure element, the reducing is. Concepts for theoretical and analytical assessment tests in the molecule -2 ) ; O 2 2O oxygen... - answers Page 58 Rule 2 Fluorine oxidation number questions and answers pdf an oxidation number of chromium in each of the numbers! Sharing, gaining, or losing electrons Cu in CuSO 4! 1 in... From +2 to 0 4F + N 2 2 O 2, O 2 2O 2-therefore oxygen reduced! Answers Page 58 Rule 2 Fluorine has an oxidation number of s = +4 5... + 3Ag + NO 3-→ Ag+ + NO 3-→ 4Zn2+ + NH4 + + 3H 2O.... Or losing electrons – que s t i on s oxidation STATES.! 'Next ' to see the comment on the Cr ( H 2O ) 3+. Agent is reduced, which means that it gains electrons, and the 3 7+ 6+ 13 → 3N...