Paper Based Questions

Question 1

Write an equation ions formed when calcium oxide reacts with water

Answer 1

CaO+H2O
—–>Ca(2+) +2OH(-)

Question 2

How to determine whether a silver halide is iodide or bromide?

Answer 2

• Add concentrated aqeuous ammonia
• Silver bromide is soluble
• Silver iodine is insoluble

Question 3

Three Marks

Explain, in terms of electrons, why chlorine is more reactive than bromine

Answer 3

1. Attraction between outer electrons and positive nucleus decreases
2. Chlorine atoms are smaller than bromine atoms
3. Chlorine gains an electron more readily than bromine

Question 4

Six Marks

Describe + Explain imbs present in methanol,methanal and methane and deduce their relative boiling points

Answer 4

1. Methanol~hydorgen bonding polar O-H bond
2. Methanal~PD-PD polar C=O bond
3. Methane~ID-ID movement of electrons within one molecule induces a dipole in adjacent molecule
4. Strength of imbs HB>pd-pd>id-id
5. Boiling points methanol>methanal>methane
6. All compounds have id-id

Question 5

Two marks

Suggest and explain why magnesium can replace calcium in carbonate shell

Answer 5

• Mg and Ca both in group two-both can react with carbonate
• So same number of outer shell electrons

Question 6

Three Marks

Describe + Explain the conditions necessary for nuclear fusion to occur

Answer 6

• High temperature
• High pressure
• Provides large enough kinetic energy to overcome the repulsion by the positive charge of the nuclei

Question 7

Three marks

Give one advantage and two disadvantages of using coal as an energy source compared to ‘cleaner’ fossil fuels

Answer 7

• Advantage~large supply
• Disadvantage~can cause respiratory problems and smog

Question 8

Two marks

Explain why CH3Cl has a permananent dipole

Answer 8

• The molecule is asymetrical
• So the charges the charges don’t cancel each other out