NCERT Solutions for Exploration Chapter 9 Atomic Foundations of Matter

A particular element (A) has one electron in its third shell. There is another element (B) with six electrons in its second shell. (i) How many electrons does A tend to give or take to become stable? (ii) What kind of ion would it form? (iii) How many electrons does B tend to give or take to become stable? (iv) What kind of ion would it form? (v) If A and B were to combine, what kind of bond would be formed? (vi) What would be the formula for the compound thus formed?

An element X has six electrons in its outer shell and forms a diatomic molecule. (i) Why would that be so? (ii) What kind of bond would it form? (iii) Draw the structure of the molecule it would form. (iv) A certain other element Y has two electrons in its second shell. Draw the structure of the molecule that X would form with Y.

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 2+ (ii) 3 Mg and 1 PO43– (iii) 2 Fe3+ and 3 O2– (iv) 3 Ca2+ and 2 SO42–

Choose 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.

Write the chemical formulae for the following compounds. (i) Aluminium nitrate (ii) Calcium oxide (iii) Ferric oxide

Write the formulae of the compounds formed from the following pairs of ions. ‒ (i) Ca2+ and Br 3+ (ii) Al and CO32– (iii) K+ and SO42– – (iv) NH4+ and Cl –

Which of the following, in Fig. 9.18, correctly represents Cl ion (Atomic number of chlorine = 17). (i) (ii) (iii) (iv)

Determine the formula unit mass of the following substances. (i) Ammonium nitrate (NH4NO3), used as a nitrogen fertiliser, which is essential for plant growth. (ii) Phosphoric acid (H3PO4), used to make phosphate fertiliser and detergents. (iii) Sodium hydrogencarbonate (NaHCO3), used to relieve acidity and helps in digestion.

Write the formulae for the compounds formed by the reaction of: (i) Magnesium and nitrogen (ii) Lithium and nitrogen (iii) Sodium and sulfur (iv) Aluminium and oxygen

Complete the Table 9.3 by writing the formulae of the compounds formed by the cations on the left and the anions at the top. LiNO3 is given as an example. Table 9.3 NO3– SO42– PO43– + NH4 Li+ LiNO3 Al3+ Cu2+

5.3 g of sodium carbonate and 6.0 g of acetic acid react to produce 2.2 g of carbon dioxide, 0.9 g of water, and 8.2 g of sodium acetate. Verify whether the law of conservation of mass is valid.

If a species has 11 protons, 12 neutrons and 10 electrons then (i) what is its atomic number and mass number? (ii) is it neutral, a cation or an anion? Explain. (iii) write its electronic configuration. (iv) name the species.

Two elements, A and B, have the following configurations — A: 2, 8, 5 B: 2, 8, 7 (i) Which element is more reactive? (ii) Will A and B form ionic or covalent bonds when they combine? Explain using electron transfer or sharing. (iii) Predict the formula of the compound they would form.

Assertion (A): Copper sulfate conducts electricity in the molten state but not in the solid state. Reason (R): Copper and sulfate ions are fixed in the lattice in molten state, while in solid state they can move freely. Choose the correct option: (i) Both A and R are true, and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, but R is false. (iv) A is false, but R is true. –

The species 27Al, 80Br and 201Hg2+ have 13, 35 and 80 protons, respectively. How many electrons and neutrons do they have?