What is the difference between a skeletal equation and balanced chemical equation? Give example. (CBSE 2007)

You might have noted that when copper powder is heated in a china dish, the surface of copper powder becomes coated with a black colour substance.(a) How has this black coloured substance formed?(b) What is that black substance?(c) Write the chemical equation of the reaction that takes place. (CBSE 2011)

Using balanced chemical equation give a difference between displacement and double displacement reaction. (CBSE 2012, 2011)

When a green iron salt is heated strongly, its colour finally changes to black and odor of burning sulphur is given out.

a. Name the iron salt.

b. Name the type of reaction that takes placed during the heating of iron salt.

c. Write the balanced chemical equation for the reaction involved. (CBSE 2008)

A, B and C are three elements which undergo chemical reactions according to the following equations.

A₂O₃ + 2B → B₂O₃ + 2A

3CSO₄ + 2B → B₂(SO₄)₃ + 3C

3CO + 2A → A₂O₃ + 3C

Answer the following questions with reasons.

a. Which element is the most reactive?

b. Which element is the least reactive?

c. What is the type of reactions listed above? (CBSE 2008)