Page 192 - Chemistry

- React the resulting solution with solution of sodium sulphate i.e

Na 2SO 4(aq) + PB(NO 3) 2(aq) PbSO 4(s) + 2NaNO 3(aq) √ ½
- Filter to obtain lead (u) sulphate as residue. √ ½
- Dry the salt of lead (u) sulphate in between the filter papers or in sunshine. √ ½]

7. a) Is one of the atoms of the same element having a different mass number from the rest,
but same atomic number with others of the same element

b) 92.2 X 28 + 4.7 X 29 + 3.1 X 30 = 28.11 ½
100  ½ 100 ½ 100 ½

8. a) Alkaline earth metals √1
b) P has the smallest atomic radius due to electrons of P are closest to the nucleus √1
c) Q (S) + 2H 2O(L) Q(OH) 2(aq) + H 2(g)

Structure and bonding
1. Ethanol contains molecules 1 which are not1 responsible for electrical conductivity
2. a) A covalent bond is formed by equal contribution of the shared electrons by the atom. 1
Co-ordinate bond is where the shared electrons are contributed by one of the atoms.1

H

b) x • H H
• x
H x x H • •
• • OR H x N H H N H
x
x • • x
• H H
H x

3. a) Have delocalized valency electrons 1
b) Aluminium is a better conductor/Aluminium has three delocalized electrons while
magnesium has 2. 1 It is resistant to corrosion.
4. In addition to vander waals forces, strong hydrogen bonds exist in ethanol. These bonds
require  more energy to break.

5. a) Is a covalent bond in which the shared pair of electrons comes from the same atom
6. Magnesium has more delocalized electrons than sodium
7. (a) Phsophorous chloride (PCl 3)

P

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