Which of the following is not a physical change?

Which of the following statements about the given reaction are correct?
3Fe(s) + 4H₂O(g) \(\rightarrow\) Fe₃O₄(s) + 4H₂(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent

Which of the following gases can be used for storage of fresh sample of an oil for a long time?

Name and state the law which is kept in mind while we balance a chemical equation.

State one basic difference between a physical change and a chemical change.

Write a balanced chemical equation with state symbols for the following reactions.
(i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
(ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Give an example of a double displacement reaction other than the reaction of barium chloride with sodium sulphate.

2g ferrous sulphate crystals are heated in a dry boiling tube.
(i) List any two observations.
(ii) Name the type of chemical reaction taking place.
(iii) Write the chemical equation of the reaction.

(i) Solution of a substance 'X' is used for testing carbon dioxide. Write the equation of the reaction of 'X' with carbon dioxide.
(ii) How is 'X' obtained? Write chemical equation.

Complete and balance the following chemical equations:
(i) CaCO₃ + HCl
(ii) Al + HCl
(iii) MnO₂ + HCI

What happens when a piece of
(a) Zinc metal is added to copper sulphate solution?
(b) Aluminium metal is added to dilute hydrochloric acid?
(c) Silver metal is added to copper sulphate solution? Write the balanced chemical equation if the reaction occurs.

You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO₃, ZnCl₂ and H₂O. In which of the above containers theses solutions can be kept?