Question

CLASS VII DP,SB SCIENCE H.W Define Chemical equation. Write the chemical equation(unbalanced) for the following reactions:- 1. When hydrogen gas react with nitrogen gas it forms ammonia gas. 2. Aluminum reacts with oxygen gas it forms aluminum oxide. 3. Sodium reacts with oxygen gas to form sodium oxide. 4. Sodium hydroxide reacts with hydrochloric acid to form sodium chloride and water.​

Answer 1

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

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.            (a)  Hydrogen gas and iron chloride are produced.

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.            (a)  Hydrogen gas and iron chloride are produced.            (b)  Chlorine gas and iron hydroxide are produced.

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.            (a)  Hydrogen gas and iron chloride are produced.            (b)  Chlorine gas and iron hydroxide are produced.            (c)  No reaction takes place.

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.            (a)  Hydrogen gas and iron chloride are produced.            (b)  Chlorine gas and iron hydroxide are produced.            (c)  No reaction takes place.            (d)  Iron salt and water are produced.

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.            (a)  Hydrogen gas and iron chloride are produced.            (b)  Chlorine gas and iron hydroxide are produced.            (c)  No reaction takes place.            (d)  Iron salt and water are produced.Ans: (a)  Hydrogen gas and iron chloride are produced.

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.            (a)  Hydrogen gas and iron chloride are produced.            (b)  Chlorine gas and iron hydroxide are produced.            (c)  No reaction takes place.            (d)  Iron salt and water are produced.Ans: (a)  Hydrogen gas and iron chloride are produced.4.       What is a balanced chemical equation? Why should chemical equations be balanced?

1.       Why does the colour of copper sulphate solution change when an iron nail is dipped in it?Ans: When an iron nail dipped in the copper sulphate solution than iron displaces copper from the copper sulphate because iron is more reactive than copper. Therefore the colour .       What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.            (a)  Hydrogen gas and iron chloride are produced.            (b)  Chlorine gas and iron hydroxide are produced.            (c)  No reaction takes place.            (d)  Iron salt and water are produced.Ans: (a)  Hydrogen gas and iron chloride are produced.4.       What is a balanced chemical equation? Why should chemical equations be balanced?Ans: A reaction which has an equal number of atoms of all the elements on both sides of the chemical equation is called a balanced chemical equation.Chemical reaction should be balanced to follow law of conservation of mass.

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Answer 2

Answer:

define chemical equation :

The representation of chemical reaction by means of symbols of substances in the form of formulae is called chemical equation.

1. N2+3H→2NH3.

2. 4Al + 3O2 → 2Al2O3 a.

3. 4 Na + O2 → 2 Na2O

4. NaOH + HCl = NaCl + H2O.

Explanation:

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