Question

A.Answer the following questions in detail.
1 Reactants react with each other when present in suitable physical states. Explain the statement by giving an example.
2. What are the characteristics of a chemical reaction?
3. During a chemical reaction, there is a change in temperature or energy. Explain.
4. Give an example of a chemical reaction in which
(a) A gas is evolved
(b) Heat is released
(c) Sunlight is required
(d) A precipitate is formed
5. Write the word and chemical equations for the reaction between the following reactants.
(a) Hydrogen and chlorine
(b) Hydrogen and oxygen
(c) Magnesium and oxygen​

Answer 1

Explanation:

2. evolution of gas , change of color, formation of precipitate , change of state .

4. a. Zn +H2SO4 => ZnSO4 + H2 (evolves)

b. C + O2 -> CO2 + heat

c. H2 + Cl2 => 2HCl ( when exposed to sunlight )

d. Agno3( aq) + NaCl (aq) => AgCl( curdy white ppt) + NaNO3( aq)

5. a.hydrogen and chlorine when exposed in sunlight gives hydrogen chloride

H2 +Cl2 =>2HCl

b. 2H2 +O2=>2H2O

hydrogen when burns in oxygen gives dihydrogen oxide or forms water with a pop sound

c. Hold a piece of magnesium ribbon over a flame . It burns with a dazzling white light , forms magnesium oxide

2Mg + O2 =>2MgO(synthesis reaction)