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You want to design a new ionic compound, where the total positive charge is 6+ and the total negative charge is 6-. Which of the following combinations gives the correct number of ions? (i) 2 Al3+ and 3 Cl- (ii) 3 Mg2+ and 1 PO4 3- (iii) 2 Fe3+ and 3 O2- (iv) 3 Ca2+ and 2 SO4 2-
Option (iii) is the correct answer. In this combination, two ferric ions Fe3+ contribute a positive charge calculated as two multiplied by plus three, totaling plus six. Three oxide ions O2- contribute a negative charge calculated as three multiplied by minus two, totaling minus six. This perfectlyRead more
Option (iii) is the correct answer. In this combination, two ferric ions Fe3+ contribute a positive charge calculated as two multiplied by plus three, totaling plus six. Three oxide ions O2- contribute a negative charge calculated as three multiplied by minus two, totaling minus six. This perfectly satisfies the requirement of having a total 6+ positive charge and 6- negative charge.
For more NCERT Solutions of Class 9 Science Exploration Chapter 9 Atomic Foundations of Matter Question Answer (2026-27)
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See lessChoose the correct statement(s) and correct the false statement(s). (i) Elements are made up of molecules and compounds are made up of atoms. (ii) The molecule of a compound is always made up of two or more atoms of the same kind. (iii) One molecule of nitrogen gas contains three nitrogen atoms. (iv) Water is made of two hydrogen atoms, covalently bonded with one oxygen atom.
Statement (iv) is correct because water contains two hydrogen atoms bonded covalently to one oxygen atom. Statement (i) is false because elements consist of identical atoms, whereas compounds consist of combined atoms. Statement (ii) is false because compound molecules contain different types of atoRead more
Statement (iv) is correct because water contains two hydrogen atoms bonded covalently to one oxygen atom. Statement (i) is false because elements consist of identical atoms, whereas compounds consist of combined atoms. Statement (ii) is false because compound molecules contain different types of atoms. Statement (iii) is false because a molecule of nitrogen gas contains two nitrogen atoms, not three.
For more NCERT Solutions of Class 9 Science Exploration Chapter 9 Atomic Foundations of Matter Question Answer (2026-27)
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See lessWrite the chemical formulae for the following compounds. (i) Aluminium nitrate (ii) Calcium oxide (iii) Ferric oxide
Aluminium ion Al3+ combines with nitrate NO3- to give aluminium nitrate Al(NO3)3. Calcium ion Ca2+ combines with oxide ion O2- in a one-to-one ratio to form calcium oxide CaO. Ferric ion Fe3+ combines with oxide ion O2- through criss-crossing valencies to form ferric oxide Fe2O3. All three formulaeRead more
Aluminium ion Al3+ combines with nitrate NO3- to give aluminium nitrate Al(NO3)3. Calcium ion Ca2+ combines with oxide ion O2- in a one-to-one ratio to form calcium oxide CaO. Ferric ion Fe3+ combines with oxide ion O2- through criss-crossing valencies to form ferric oxide Fe2O3. All three formulae ensure overall electrical neutrality of the ionic compounds.
For more NCERT Solutions of Class 9 Science Exploration Chapter 9 Atomic Foundations of Matter Question Answer (2026-27)
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See lessWrite the formulae of the compounds formed from the following pairs of ions. (i) Ca2+ and Br- (ii) Al3+ and CO3 2- (iii) K+ and SO4 2- (iv) NH4+ and Cl-
For Ca2+ and Br-, criss-crossing the valencies gives calcium bromide as CaBr2. For Al3+ and CO3 2-, balancing charges requires two aluminium ions and three carbonate groups, producing Al2(CO3)3. For K+ and SO4 2-, two potassium ions balance one sulfate ion, yielding K2SO4. For NH4+ and Cl-, both havRead more
For Ca2+ and Br-, criss-crossing the valencies gives calcium bromide as CaBr2. For Al3+ and CO3 2-, balancing charges requires two aluminium ions and three carbonate groups, producing Al2(CO3)3. For K+ and SO4 2-, two potassium ions balance one sulfate ion, yielding K2SO4. For NH4+ and Cl-, both have unit charges, producing ammonium chloride NH4Cl. All formulae represent fully neutral ionic compounds.
For more NCERT Solutions of Class 9 Science Exploration Chapter 9 Atomic Foundations of Matter Question Answer (2026-27)
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See lessWhich of the following, in Fig. 9.18, correctly represents Cl- ion (Atomic number of chlorine = 17).
Option (iii) is the correct representation of the Cl- ion. A chlorine atom possesses an atomic number of 17, meaning it normally contains seventeen electrons with the shell configuration 2, 8, 7. Upon forming a chloride anion Cl-, it gains one electron to attain a stable octet, totaling eighteen eleRead more
Option (iii) is the correct representation of the Cl- ion. A chlorine atom possesses an atomic number of 17, meaning it normally contains seventeen electrons with the shell configuration 2, 8, 7. Upon forming a chloride anion Cl-, it gains one electron to attain a stable octet, totaling eighteen electrons. Diagram (iii) accurately displays this electronic configuration containing 2 electrons, 8 electrons and 8 electrons.
For more NCERT Solutions of Class 9 Science Exploration Chapter 9 Atomic Foundations of Matter Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-9/
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