Practise Questions

• Protons are positively charged particles found in the nucleus.
• Neutrons have no charge, they are also located in the nucleus.
• The nucleus is the centre of an atom
• Electrons are negatively charged particles that orbit around the nucleus
• The number of protons is equal to the atomic number
• Atoms can gain or lose electrons to form ions.
• The mass number is the total number of protons and neutrons in an atom
• A universal indicator turned blue. What is the pH value of the solution?

  9
• Why are nanoparticles effective in very small quantities?

  They have a higher surface area to volume ratio
• Give one advantage of using nanoparticles in sun creams.

  Better Coverage
• Give one disadvantage of using nanoparticles in sun creams.

  Potential cell damage
• Suggest two reasons why 9 carat gold is often used instead of pure gold to make jewellery.

  9 carat is cheaper

  24 carat is soft
• Propane (C3H8) is used as a fuel. Complete the equation for the complete combustion of propane. C3H8 + 5O2 → 3 .............................. + 4 .................................

  (3) CO2

  (4) H2O
• Water from a lake in the UK is used to produce drinking water.What are the two main steps used to treat water from lakes?

  filtration by passing through filter beds to remove solids

  sterilisation to kill microbes
• Explain why it is more difficult to produce drinking water from waste water than from water in lakes.


  water needs more as it contains more microbes
• Why is producing drinking water from sea water expensive?

  High energy requirement
• Explain how a covalent bond holds two atoms together.

  electrostatic force of attraction between shared pair of negatively charged electrons and both positively charged nuclei
• Explain, in terms of particles, how and why the rate of reaction changes during the reaction of calcium carbonate with hydrochloric acid.

  acid particles used up so concentration decreases so less frequent collisions so rate decreases

   
• Explain how increasing the pressure of the reactants will affect the amount of ethanol produced at equilibrium.

  more ethanol will be produced because system moves to least
• Describe, as fully as you can, what happens when magnesium atoms react with oxygen atoms to produce magnesium oxide.

  Magnesium loses electrons and oxygen gains electrons. two electrons gives full outer shells

   
• Silicon dioxide has a very high melting point. Other substances are added to silicon dioxide to make glass. Glass melts at a lower temperature than silicon dioxide. Suggest why

  Weaker bond
• Glass can be coloured using tiny particles of gold. Gold is a metal. Describe the structure of a metal.

  Lattice of positive ions with delocalised electrons