A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.

>

>

Chapter 1 NCERT Class 10 Science SOLUTIONS

17. A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.

Question:

A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.

Answer:

The shiny brown colored element X is called copper which when heated in air forms copper oxide. It is of black colour.

More NCERT Questions

Download Free PDF

(All Q's of this Chapter solved)

question pointer

Explain the following terms with one example each: (a) Corrosion (b) Rancidity.

question pointer

Oil and fat-containing food items are flushed with nitrogen. Why?

question pointer

Why do we apply paint on iron articles?

question pointer

Explain the following in terms of gain or loss of oxygen with two examples each: (a) Oxidation (b) Reduction

question pointer

What do you understand by precipitation reaction? Explain with examples.

question pointer

In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.

question pointer

Write one equation each for the decomposition reactions where energy is supplied in the form of heat, light or electricity.

question pointer

Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.

question pointer

Why is respiration considered an exothermic reaction? Explain.

question pointer

What is meant by exothermic and endothermic reaction? Give an example.

question pointer

Write the balanced chemical equations for the following reactions:(a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water(b) Zinc + Silver nitrate → Zinc nitrate + Silver(c) Aluminium + Copper chloride → Aluminium chloride + Copper(d) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride

question pointer

Balance the following chemical equations: (a) HNO3 + Ca(OH)2 →Ca(NO3)2 + H2O (b) NaOH + H2SO4 → Na2SO4 + H2O (c) NaCl + AgNO3 → AgCl + NaNO3 (d) BaCl2 + H2SO4 → BaSO4 + HCI

question pointer

Translate the following statements into chemical equations and then balance them.(a) Hydrogen gas combines with nitrogen to form ammonia.(b) Hydrogen sulfide gas burns in the air to give water and sulfur dioxide.(c) Barium chloride reacts with aluminum sulphate to give aluminum chloride and a precipitate of barium sulphate.(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.

question pointer

What is a balanced chemical equation? Why should chemical equations be balanced?

question pointer

What happens when dilute hydrochloric acid is added to iron filings? (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.

question pointer

Fe2O3 + 2Al → Al2O3 + 2Fe What type of reaction is given above? (a) Combination reaction (b) Double displacement reaction. (c) Decomposition reaction. (d) Displacement reaction

question pointer

Which statement is false regarding the reaction given below? 2PbO(s) + C(s) —> 2Pb(s) + CO(g) (a) Lead is reducing. (b) Carbon dioxide is getting oxidised.(c) Carbon is getting oxidised.(d) Lead oxide is getting reduced.

question pointer

Identify the substances that are oxidised and the substances which are reduced in the following reactions:

question pointer

Give an example of a double displacement reaction other than the one given in Activity 1.10 (NCERT). (i) 4Na(s) + O2(g) — 2Na2O(s) (ii) CuO (s) + H2(g) — Cu (s) + H2O(l)

question pointer

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

question pointer

Why is the amount of gas collected in one of the test tubes in text book Activity 1.7 (i.e., electrolysis of water) double of the amount collected in the other? Name this gas.

question pointer

A solution of a substance ‘X’ is used for white washing.(a) Name the substance ‘X’ and write its formula.(b) Write the reaction of the substance ‘X’ named in (a) above with water.

question pointer

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 a hydrochloric acid solution(in water) to produce sodium chloride solution and water.

question pointer

Write the balanced equation for the following chemical reactions :(i) Hydrogen + Chlorine → Hydrogen chloride(ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride(iii) Sodium + Water → Sodium hydroxide + Hydrogen

question pointer

Why should a magnesium ribbon be cleaned before burning in air?

question pointer

Write the balanced chemical equation for the following and identify the type of reaction in each case:

© 2026, Agrawal Group of Publications All rights reserved.