Question

State one example is characterized by the following along with chemical equation also change in the state evolution of gas change in temperature change in colour formation of

Answer 1

Answer:

(a) Change in state: The combustion reaction of candle wax (solid) melts initially to produce molten wax (liquid) and then produces carbon dioxide (gas) and water vapour (liquid). So, in this reaction, state of matter gets changed from solid to liquid and gas.

(b) Evolution of gas: When zinc granules react with dilute sulphuric acid in a flask, hydrogen gas evolves and zinc sulphate solution is formed.

Zn+ H2SO4→ ZnSO4+ H2↑⏐

(c) Change in temperature: When quicklime reacts with water, slaked lime is formed with a release of large amount of heat, causing change in temperature in the reaction mixture.

CaO +H2O →Ca(OH)2 + Heat

Explanation:

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Answer 2

Concept Introduction:-

In the chemical reaction, one or more substances—also known as reactants—are changed into one may be more additional substances—also known as products.

Explanation:-

A question has been provided to us

We need to find the solution to the question

$1$. Evolution of gas:

The chemical reaction between zinc and dilute sulphuric acid is characterized by the evolution of hydrogen gas.

$Zn(s)+H_2SO_4(aq)\rightarrow ZnSO_4(aq)+H_2(g)$

$2$. Change in colour:

The reaction between the lead nitrate solution and potassium iodide solution.

$Pb(NO_3)_2(aq)+2KI\rightarrow PbI_2(s)+2KNO_3(aq)$

In this reaction colour changes from colourless to yellow.

$3$. Formation of precipitate:

The action of Barium Chloride on sodium sulphate.

$BaCl_2(aq)+Na_2SO_4(aq)\rightarrow BaSO_4(s)+2KNaCl(aq)$

$4$. Change in temperature:

The action of dilute sulphuric acid on zinc:

$Zn(s)+H_2SO_4(aq)\rightarrow ZnSO_4(s)+H_2(g)$

In this reaction, heat is evolved.

$5$. Change in the state:

When the wax is burnt in the form of the wax candle then water and carbon dioxide are formed. Wax is solid, water is a liquid whereas carbon dioxide is a gas.

Final Answer:-

The correct answer is the chemical reaction between zinc and dilute sulphuric acid is characterized by the evolution of hydrogen gas.

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