What is the differences between a chemical symbol and a chemical formula?

How many atoms of zinc and chlorine are present in zinc chloride (ZnCl₂)?

Write the formulae of the following compounds using the four-step method.

1. Magnesium chloride (containing magnesium and chlorine)
2. Zinc oxide (containing zinc zinc oxygen)

Write the formulae of the following compounds using the four-step method.

1. Lead nitrate (containing lead and nitrate; the valency of lead is 2)
2. Copper sulphate (containing copper and sulphate; the valency of copper is 2)

Multiple choice questions:

1. The symbol of sulphur is __________.
   1. Ca
   2. S
   3. Cl
   4. K
2. Which of the following is not an element?
   1. Mg
   2. Au
   3. CO₂
   4. Fe
3. Which of the following is not a compound?
   1. ZnO
   2. AgCl₂
   3. AlCl₃
   4. He
4. Which of these statements about compounds is false?
   1. The components of a compound are combined chemically.
   2. The components of a compound are mixed in a fixed ratio.
   3. The individual components of a compound retain their properties.
   4. Compounds and their components have different properties.
5. Which of these is the correct way to write the formula of common salt?
   1. NACL
   2. NaCL
   3. NacL
   4. NaCl
6. In SO₂ there are ____________ sulphur atom/atoms and __________ oxygen atom/atoms.
   1. 1, 2
   2. 2, 1
   3. 2, 2
   4. 1, 1