What is observed when a pinch of sodium hydrogen carbonate is added to 2 mL of acetic acid taken in a test tube? Write the chemical equation for the reaction involved in this case.

When a pinch of sodium hydrogen carbonate is added to 2 mL of acetic acid taken in a test tube carbon dioxide gas and water will form. Carbon dioxide gas is evolved with brisk effervescence. The chemical equation is as follows: NaHCO 3 + CH 3 COOH → CH 3 COONa + H 2 O + CO 2 Sodium Acetic acid Sodium acetate hydrogen carbonate

What would a student report nearly after 30 minutes of placing duly cleaned strips of aluminium, copper, iron and zinc in freshly prepared iron sulphate solution taken in four beakers?

When duly cleaned strips of aluminium, copper, iron and zinc in freshly prepared iron sulphate solution taken in four beakers the report after half an hour are as follows; (i) Case 1 = Aluminium displaces the iron from iron sulphate and the colour of the two solutions changes from green to brown. (ii) Case 2 = No change takes place when the copper strip is dipped in an iron sulphate solution. (iii) Case 3 = No change will be observed when iron strips are dipped in an iron sulphate solution. (iv) Case 4 =The colour of the solution changes from green to colourless when zinc is added to iron sulphate solution. Zinc is more reactive than iron so the light green colour of the solution turns colourless.

On heating blue coloured powder of copper (II) nitrate in a boiling tube, black copper oxide, O 2 and a brown gas X is formed. (a) Identify the type of reaction and the gas X. (b) Write balanced chemical equation of the reaction. (c) Write the pH range of aqueous solution of the gas X.

a) On heating blue coloured powder of copper (II) nitrate in a boiling tube, black copper oxide, O 2 and a brown gas X is formed. It represents a decomposition reaction in which a single reactant decomposes to give different products. The gas X is Nitrogen dioxide. b) It represents a thermal decomposition reaction in which a single reactant decomposes to give different products. The balanced chemical equation of the reaction is: 2 Cu ( NO 3 ) 2 ( s ) → Heat 2 CuO ( s ) + 4 NO 2 ( g ) + O 2 ( g ) c) NO 2 dissolves in water to form an acidic solution. It will have the pH range between 0 to 7. The oxides of non-metals are generally acidic in nature.

What is observed when a solution of sodium sulphate is added to a solution of barium chloride taken in a test tube ? Write equation for the chemical reaction involved and name the type of reaction in this case.

When a solution of sodium sulphate is added to a solution of barium chloride a white precipitate of barium sulphate is formed. The chemical reaction involved is can be given as, Na 2 SO 4 ( aq ) ( sodium sulphate ) + BaCl 2 ( aq ) ( Barium chloride ) → BaSO 4 ( s ) ( Barium sulphate ) + 2 NaCl ( aq ) ( sodium chloride ) It is an example of double displacement reaction.

1 g of copper powder was taken in a China dish and heated. What change takes place on heating? When hydrogen gas is passed over this heated substance, a visible change is seen in it. Give the chemical equations of reactions, the name and the colour of the products formed in each case.

When copper powder is heated in a China dish the brown powder turns black due to the formation of copper oxide. It is an oxidation reaction and oxygen acts as an oxidising agent. 2 Cu brown + O 2 → heat 2 CuO black When hydrogen gas is passed over copper oxide and heated, the brown colour is restored due to the formation of copper metal. It is a reduction reaction where copper oxide gets reduced into copper and hydrogen gas acts as a reducing agent. 2 CuO black + H 2 → heat Cu brown + H 2 O

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 1 - Chemical Reactions and Equations>CBSE-2021 Term I>Q 17

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Which one of the following reactions is categorised as thermal decomposition reaction?

100% studentsanswered this correctly

Important Questions on Chemical Reactions and Equations

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 1 - Chemical Reactions and Equations>CBSE-2021 Term I>Q 18

The pair(s) which will show displacement reaction is/are

(i) $NaCl$ solution and copper metal

(ii) ${AgNO}_{3}$ solution and copper metal

(iii) ${Al}_{2} {({SO}_{4})}_{3}$ solution and magnesium metal

(iv) ${ZnSO}_{4}$ solution and iron metal.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 1 - Chemical Reactions and Equations>CBSE-2023 (Delhi - I)>Q 20

When aqueous solutions of potassium iodide and lead nitrate are mixed an insoluble substance separates out. The chemical equation for the reaction involved is:

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 1 - Chemical Reactions and Equations>CBSE-2023 (Delhi - I)>Q 21

A metal ribbon

' X'

burns in oxygen with a dazzling white flame forming a white ash

' Y'

. The correct description of

X, Y

and the type of reaction is:

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 1 - Chemical Reactions and Equations>CBSE-2023 (Delhi - I)>Q 23

While electrolysing water before passing the current some drops of an acid are added. Why? Name the gases liberated at cathode and anode. Write the relationship between the volume of gas collected at anode and the volume of gas cathode.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 1 - Chemical Reactions and Equations>CBSE-2023 (Delhi - I)>Q 24

What is observed when silver chloride is exposed in sunlight? Give the type of reaction involved.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 1 - Chemical Reactions and Equations>CBSE-2023 (Delhi - I)>Q 25

Suggest a safe procedure for diluting a strong concentrated acid.

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